Special construction scheme for high-fill subgrade I. Overview of the project Highway reconstruction project from Jianou Fangkou to Shunchang Street of Provincial Highway 204, the high-fill subgrade of this project is in bid ***3. The section of subgrade is K2 1+520 ~ K2 1+630 (length 1 10m), and the average width of subgrade is 32.0 1m, k23+11. Construction preparation 1) construction survey: organize construction technicians to recheck the leveling points and traverse points of the whole line, and the survey results have been approved by the supervisor and used for construction lofting. 2) Power consumption for construction: a 200KW diesel generator is provided for standby. 3) Joint review of drawings: The joint review of design drawings has been completed, and the problems existing in the design will be reported to the supervisor, the owner and the design institute for handling. 4) All kinds of temporary facilities, mechanical equipment and construction personnel have been put in place. 5) Tests and tests of various materials and mixture ratios have been completed. 6) The construction period is planned to start on March 5th, 20 1 1 year and end on June 30th, 201/year. Three. Construction scheme The main construction scheme and subgrade filling of auxiliary facilities adopt layered filling and compaction method, based on the standard operation method of "three-stage, four-stage and eight-process" vertical layering and slope brushing synchronization. The filling width of each layer of embankment should exceed the designed width of embankment by 50cm, so as to ensure that the edge of embankment after subgrade slope trimming has enough compactness and complete temporary drainage works. Before construction, the test section should be made according to the packing situation and reasonable process parameters (maximum dry density, optimum water content, compaction times, etc.). ) to be determined, in order to fully guide the construction. Before construction, clean the subgrade surface, and the original ground should be compacted to meet the requirements. When filling, according to the traffic volume of each vehicle, spread the square grid on the site, control the thickness of the virtual paving, level the bulldozer at first, level the grader at last, and use the sheep's foot roller and 20t heavy vibratory roller for layered compaction. In the filling section of shoulder retaining wall, the retaining wall should be built first, and then the subgrade should be filled. Before subgrade construction, drainage works, anti-seepage facilities and temporary drainage measures near the construction site should be done well. During subgrade construction, the corresponding transverse and longitudinal slopes should be drained in an organized way. Subgrade drainage works include masonry drainage ditch and intercepting ditch. Subgrade protection engineering includes plant protection and engineering protection. Subgrade protection and drainage should follow the construction sequence of subgrade forming. 1. Embankment construction method Embankment filling adopts vertical and horizontal layered filling compaction method and "three stages, four sections and eight processes" technology. Before construction, the test section should be made according to the packing situation and the reasonable process parameters should be determined. After approved by the supervision engineer, fully guide the construction. The four-section subgrade filling construction is arranged along the road in four sections: filling area, leveling area, rolling area and inspection area, and the longitudinal length of each section is divided according to the site conditions. The subgrade filling construction work area is arranged in four sections, so that each working procedure can operate relatively independently without interference, give full play to production efficiency, improve production efficiency and ensure project quality. The concrete contents of the four sections are as follows: the fill area is the area where site cleaning and basement treatment have been completed, and it shall be reported to the supervision engineer for approval after passing the inspection. During construction, according to the loose paving thickness determined by the test and the load capacity of the car, the distance before and after unloading the soil is determined after calculation to ensure that the loose paving thickness meets the requirements. The leveling area is the filling area of dump trucks, and it is also the leveling construction area of bulldozers and graders. During leveling operation, bulldozers are used for rough leveling, and the earth piles unloaded by dump trucks are initially leveled to form a rough leveling surface. Then, graders are used for final leveling, and the filling surface is carefully leveled according to the specification requirements, forming a lateral drainage slope of 3-4% on both sides of the top surface of the center of the line. The rolling area is specially designed for the road roller construction operation area, and the rolling can only be carried out after passing the inspection and being approved by the supervision engineer. The test area is the area where the compaction process is completed according to the number of rolling passes determined by the test, and the compaction test can be carried out with the approval of the supervision engineer, and it is the working area for testing the compaction density and other indicators. After passing the inspection, with the approval of the supervision engineer, it will enter the filling operation area for recycling and form a new filling area. Eight-process subgrade filling construction process is carried out according to the following eight steps: site cleaning-basement treatment-layered filling-paving and leveling-mechanical rolling-inspection and appraisal-subgrade renovation. Dike construction must adhere to the "three lines and four degrees". Three lines, namely the center line and two sideline lines, insert a small red flag every 10m on the three lines to define the control points of the center line and sideline lines; The four degrees are: thickness, compactness, camber and flatness. Control the thickness of subgrade layers to ensure the compactness; Control the road camber to ensure the timely drainage of rainwater; Control the smoothness, ensure the subgrade compaction is uniform, and the subgrade will not accumulate water when it rains. 2. Construction preparation, basement treatment (1) Tree cutting, root digging and weeding Trees and shrubs in subgrade area (occupied by embankment and cutting) are cut down or transplanted before construction. The cut trees are piled up outside the subgrade land in an orderly manner, and properly treated. The turf, crop roots and tree roots within the subgrade land are all removed, and the pits in the filled subgrade area are leveled and compacted. (2) When excavating the stepped embankment, when the natural transverse slope or longitudinal slope of the ground is steeper than 1: 5, the original ground will be excavated into steps with a width greater than 2m and a height of 0.3m to meet the requirements of paving and compacting equipment operation. The top of the steps is made into a slope of 2% ~ 4%. In principle, sand does not dig steps, but turns the topsoil 200 ~ 300 mm below the original ground. For the inclined rock basement with thin overburden, when the cross slope of the ground is 1: 5 ~ 1: 2.5, the overburden should be removed and the bedrock should be dug into steps. (3) Original ground treatment After the original ground cleaning, the middle piles and construction side piles of subgrade shall be restored in time, and the piles shall be marked manually with lime to guide the mechanical construction. Use bulldozer to level the gray line in situ to form a single slope or double slope arch, which is convenient for drainage. After the above work is completed, the original ground should be treated as follows. Roll with a 20t smooth roller for 3 ~ 4 times. In the process of rolling, local spring phenomenon appears, which is removed manually, mixed with appropriate amount of lime, and rolled again to the required degree of compaction. For the sections with poor climate, low temperature and difficult sun-turning, artificial bouquets should be treated with 5% hydrated lime of 20cm, and mixed with plough, road mixer or rotary tiller for 3 ~ 4 times. Visually, there are no gray stripes, gray stripes and uniform colors, and the overall horizon is uniform. After the water content is reached, it will be shaped by grader and rolled to the required density by smooth roller. (4) Key points of filling construction of high-fill embankment When filling the embankment horizontally in this bid section, the embankment shall be filled horizontally in layers at intervals of 20 ~ 25 cm according to the full width of the whole section, and rolled layer by layer. For the road sections with original ground longitudinal slope greater than 12%, longitudinal layered filling shall be carried out first, and the maximum loose laying thickness of each layer shall not exceed 30cm. After the alignment is adjusted, all sections shall be horizontally layered and constructed as a whole. In the process of construction, when filling 2 ~ 3 floors, it is necessary to carry out retest lofting, determine the middle pile, measure the elevation, and set the filling boundary line by lofting, so as to ensure the subgrade filling width and the formed subgrade linear shape. 1), filler selection: according to the characteristics of large earthwork volume of subgrade in this contract section, select hard rock blocks with good gradation that meet the requirements of specifications as fillers, and the maximum particle size shall not exceed 2/3 of the layer thickness. Rock-filled embankment shall be filled and compacted in layers, and the thickness of loose paving in layers shall not be greater than 0.4m, so as to ensure the compactness of subgrade and avoid subgrade subsidence caused by the gap between stones. The particle size of the filler below the top surface of subgrade is 50cm, and the graded sand material with particle size not greater than 10cm is selected and compacted in layers. When filling in layers, the transportation route of stone should be arranged, and there should be a special person to command, and the horizontal filling should be carried out in layers, first low and then high, then discharged to both sides, then discharged to the middle, and leveled with a large bulldozer. Individual uneven places are manually filled with fine stones and leveled with stone chips. When the stone grading is poor, the particle size is large, the filling layer is thick, and the gap between stones is large, ballast and debris can be embedded in the gap on the surface of each layer until the gap is filled. When paving stones with a particle size greater than 25cm manually, the large stones should be paved first, with the big face down and the small face up, and placed smoothly, then leveled with small stones, caulked with stone chips, and finally compacted. If there is a great difference in lithology between the fillers of rock-filled embankment, the fillers with different lithology should be filled in layers or sections. In a stone-filled embankment in paddy field or soft soil area, after foundation treatment, stones will be laid under the embankment. Fill in large stones first, then use small stones or ballast to fill the joints, level and compact. 2) Accumulated slope: In the filling section of the shoulder-less retaining wall, firstly, hard stone with a particle size greater than 30cm and not less than 15cm is manually selected for stepped staggered masonry slope, and the large masonry surface of each layer is firmly placed downwards, and small stones are closely embedded between stone joints, and the slope and thickness meet the design requirements. 3) Paving and leveling: when filling layer by layer, arrange the transportation route of the stone, and assign special personnel to command it. It will be horizontal layer by layer, first low and then high, then discharge it to both sides, and then discharge it to the middle, and level it with a large bulldozer, so that the level will be roughly flat, and the uneven parts will be leveled with fine particles, and individual sharp corners will be smashed off with a sledgehammer. Each layer of filler should be uniform, and different fillers should not be mixed. 4) Check the loose laying thickness: set a section every 20m along the longitudinal direction, with 3-5 measuring points for each section, measure the elevation of each point with a level, and check the loose laying thickness relative to the lower elevation, and the loose laying thickness of each layer shall not be greater than 40cm. 5) Compaction: 20t vibratory roller shall be used for layered compaction, and 250t impact roller shall be used for compaction at least 20 times every 2m filling height. The number of rolling passes shall be determined according to the construction results of the process test section and approved by the supervision engineer as the control parameter. Control compaction quality with compaction speed and rolling times, and make compaction records. After compaction, the top surface must be stable, no longer sinking, the stones are dense, and the surface is smooth. After the compaction of each layer is completed, the settlement of subgrade should be observed and recorded. If necessary, it shall be repaired in time, but the repair thickness shall not exceed the thickness of a layer of filler. 6) Quality inspection: it mainly includes the thickness of filler and filling layer, the section size of subgrade filling, the longitudinal and transverse uniformity, flatness and compactness of filling layer. Only after the self-inspection is qualified and reported to the supervision engineer for acceptance can the next layer be filled. In order to ensure the filling quality of high-fill subgrade and the stability of slope, priority must be given to the construction of high-fill embankment so as to leave a certain settlement period. According to the design section and the over-filling width required by the specification, the toe of embankment slope is accurately set out. After the topsoil is removed, the basement shall be compacted and reinforced according to the design and specification requirements to ensure that the basement reaches the specified degree of compaction. Strictly control the quality of fillers and regularly test the technical indicators of fillers. If the sources of fillers are different and their properties are quite different, they should be filled in layers; For the flooded part of high fill embankment, the filler with high water stability and good water permeability should be used, and its slope ratio should not be less than1:1.75; When the high fill base on one side of the half-fill and half-dig is a slope, horizontal steps should be dug as required. After each layer is filled, slope protection should be done in time to prevent rain erosion. Pay attention to drainage during construction in rainy season. At the junction of filling and excavation, some temporary drainage ditches will be built to prevent rain from washing the whole slope. High-fill embankment should be reasonably buried with settlement observation points, and settlement observation should be carried out according to regulations to monitor the stability of embankment. The construction technology of high embankment filling is shown in Figure 3 below. Special construction scheme for dynamic compaction of special subgrade 1). The purpose of dynamic compaction is to improve the effective reinforcement depth of subgrade and ensure the consistent settlement of subgrade. 2) Surface cleaning and earthwork allocation: remove the organic matter on the surface, and level the construction site before dynamic compaction, so that the site has the construction conditions of dynamic compaction machinery. 3) Before dynamic compaction, try to pave the test section and determine the tamping parameters. Generally, the interval between the main rammer and the auxiliary rammer is 2 weeks. After the main rammer and the auxiliary rammer are completed, the full rammer shall be carried out, and the full rammer shall be rammed with wide points. The type of dynamic compaction machine should be selected according to the degree of compaction, void ratio and dynamic compaction machine: the average settlement of the last two blows should not be greater than 50mm, and the ground around the tamping pit should not be excessively raised. Dynamic compaction shall keep a safe distance of 2m from the shoulder edge; The safe distance between dynamic compaction and buildings should not be less than 50m. Ramming surface position is the original ground, and it is rammed every 4m. Road sections with geogrids are not rammed, and embankment sections with retaining walls and embankment sections close to structures are not rammed. 4) Construction steps: 1. Mark the position of the first tamping point on the leveled site and measure the site elevation. 2, crane in place, make the rammer in the position of tamping point. 3. Measure the elevation of hammer top before tamping. 4. Lift the rammer to a predetermined height. When the rammer falls freely, put down the hook and measure the elevation of the top of the rammer. 5. Repeat step 4, and complete the tamping of 1 point according to the tamping times and control standards of design and trial tamping. 6. Repeat steps 2-5 to complete the tamping of all tamping points for the first time. 7. Change the tamping point, fill the tamping pit with bulldozer, measure the elevation of the site, and stop for a specified gap time until the water pressure in the excess gap in the soil dissipates. 8. Complete all tamping times one by one according to the above steps, and measure the site elevation after tamping. 5), construction technology 1, trial tamping Before the formal dynamic compaction construction, trial tamping should be carried out, and a representative site should be selected for trial tamping. K24+390~K24+440 is designated as the test section. After the trial tamping test is completed and the intermission period meets the conditions, the in-situ test and geotechnical test should be carried out, and the dynamic penetration test should be carried out. Determine the tamping energy according to the test results of trial tamping. The rammer adopts a cylindrical hammer body with a bottom area of 2.25m and four exhaust holes with a diameter of 25cm. The rammer adopts crawler crane. Before construction, dynamic compaction parameters should be tested in representative sites according to the preliminarily determined dynamic compaction parameters, and the test results should be compared with the test data before compaction to detect dynamic compaction parameters. According to the trial ramming, the height of the rammer is preliminarily determined to determine the ramming times when the average settlement of the last two blows at the same point is not more than 5cm. 2. After the subgrade in the dynamic compaction section is leveled, the possible average ground deformation after dynamic compaction is estimated in advance, and the ground elevation before tamping is determined accordingly. 3. According to the design of construction drawings, arrange the dynamic compaction area, mark the position of tamping points, and fix the tamping points by pouring white lime into the through holes. The tamping points are arranged in a plum blossom shape with a spacing of 4m. 4. Lift the rammer to a predetermined height by dynamic compaction. When the rammer falls freely, put down the hook and measure the elevation of the hammer top. If the rammer is skewed due to the inclination of the pit bottom, the pit bottom should be leveled in time. After the first tamping at the tamping point is completed, the tamping machine will be filled with bulldozer and the elevation of the site will be measured. After the site is leveled, the surface is tamped with full rammer, and the rammer points are arranged in plum blossom shape, and the rammer points overlap each other by d/4. After the completion of dynamic compaction, the site shall be leveled and rolled. After the compaction degree meets the requirements, it will be transferred to subgrade filling construction. 6) Check the quality, filling thickness and surface smoothness of the filler during the test, inspection and visa. On the basis of meeting the specified standards, the degree of compaction shall be measured, and the sand filling method or other appropriate methods required by the contract documents shall be adopted, and each compacted layer shall be sampled according to the requirements of the specification, and the inspection results shall be recorded in a special form. After the project quality inspection engineer has passed the inspection, please ask the supervision engineer to allow the concealed visa after passing the sampling inspection. Those who do not meet the standards should be supplemented or reworked until they are qualified. Four. Quality assurance system 1) implements the system of personnel allocation and posts creation for construction personnel, and handles quality problems in time. 2) For key working procedures and concealed works, technical disclosure shall be conducted by professional technicians in the whole process. 3) The laboratory shall designate a special person to be responsible for subgrade geotechnical test, and designate a special person to conduct on-site inspection and sampling test frequently. 5) The survey team will assign special personnel to be responsible for lofting survey and data arrangement until verification. 6) The project intends to implement the quality inspection quota system, and conduct daily inspection and spot check on the quality of the construction site. Supervision inspection and acceptance after self-inspection is qualified. 7) This project implements a three-level management quality assurance system: the quality inspector of the construction team will report to the quality inspection engineer of the management department after passing the self-inspection, and finally report to the supervision engineer for review. The function distribution and interrelation of the internal quality management system are as follows: 8) Quality inspection organization and operation mode The operation mode of the quality management organization of this project is as follows: 5. Safety assurance measures: The project management department sets up a safety leading group, the members of which are Peng Qiangkun, the team leader, Zhai, the team members are Lin Xiangqiang,, Sean, and the management department implements a safety inspection system for this sub-project and a safety supervision system for on-site construction technicians. Warning signs should be set up on the construction site, with emphasis on safety precautions for electricity consumption. All construction personnel must wear safety helmets, and at the same time, they should always carry out safety education for on-site personnel. The construction team should have full-time security officers on duty. Measures for environmental protection and civilized construction of intransitive verbs: 1) Do a good job of intercepting and draining water before construction, keep the drainage in good condition, and prevent waste water, waste engine oil and waste diesel oil from being discharged into farmland and vegetable fields, so as not to cause siltation and erosion. 2) Abandoned materials for subgrade excavation must be piled up in the designated spoil ground, leveled and compacted, and shall not be piled up at will. 3) Take effective measures such as sprinkling water on temporary roads in dry season to prevent dust from polluting the surrounding environment, and keep temporary roads unblocked in rainy season. 4) Take effective measures such as noise elimination for noise generated by mechanical equipment and process operation, and try to avoid construction at night. 5) Powdered foam materials shall be transported in bags and stored in the work shed. 6) All materials on the construction site must be stacked in the designated location, and it is forbidden to place them in a random way to ensure the orderly construction. 7) Protective articles must be worn on the construction site according to regulations, and uncivilized construction behavior is strictly prohibited. Schedule 1, construction process flow chart (see schedule), schedule 2, staffing table of this sub-project (see schedule), schedule 3, schedule 1: construction process block diagram, schedule 2: staffing table number of this project, technical post name, remarks 1 project manager engineer 2, chief engineer of ginger project, 3 engineers, 4 engineers, 5 engineers, 6 quality inspection engineers, 7 testing engineer 8 survey engineers. 9 Construction Team Leader Engineer 10 Builder 1 1 Technician 10 Pugong 301314/5 Schedule 3: ListNo. of Mechanical Equipment of this Sub-project, Equipment Name, Specification, Model and Quantity (Taiwan) Remarks 60. 602 3 road roller ZL502 4 dump truck liberation 10t8 5 rock drill 5 6 generator 200KW 1 7 generator 500KW 1 8 dynamic compaction machine digging 50T 1.