CN117051809A - Combined construction method for pre-ramming and humidifying dynamic compaction of unordered high-fill site - Google Patents
Combined construction method for pre-ramming and humidifying dynamic compaction of unordered high-fill site Download PDFInfo
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- 238000010276 construction Methods 0.000 title claims abstract description 63
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- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 133
- 238000002347 injection Methods 0.000 claims abstract description 76
- 239000007924 injection Substances 0.000 claims abstract description 76
- 238000000034 method Methods 0.000 claims abstract description 47
- 230000002787 reinforcement Effects 0.000 claims abstract description 11
- 239000002689 soil Substances 0.000 claims description 77
- 239000008239 natural water Substances 0.000 claims description 20
- 238000005553 drilling Methods 0.000 claims description 19
- 238000012544 monitoring process Methods 0.000 claims description 15
- 230000003068 static effect Effects 0.000 claims description 13
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D3/00—Improving or preserving soil or rock, e.g. preserving permafrost soil
- E02D3/02—Improving by compacting
- E02D3/046—Improving by compacting by tamping or vibrating, e.g. with auxiliary watering of the soil
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- E—FIXED CONSTRUCTIONS
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Abstract
The invention belongs to the technical field of geotechnical engineering construction, and particularly provides a method for pre-ramming and humidifying dynamic compaction combined construction of a disordered high-fill site, which comprises the following steps: 1) Detecting cracks and holes in a target site; 2) Pre-ramming to eliminate cracks and hollows in a target site; 3) Injecting water into the pre-compacted target site for humidification; 4) And carrying out dynamic compaction construction on the humidified target site until the target site reaches the requirement. The method solves the problems of uneven humidification and poor reinforcement effect faced by the existing dynamic compaction foundation treatment of the unordered high-fill land, avoids the problem of uneven water injection humidification caused by uneven formation at the upper and lower parts, and has the characteristics of good treatment effect, high construction speed and small residual settlement.
Description
Technical Field
The invention belongs to the technical field of geotechnical engineering construction, and particularly relates to a pre-ramming and humidifying dynamic compaction combined construction method for a disordered high-fill site.
Background
The western loess hilly and gully regions of China have the advantages of fluctuating topography, less gully longitudinal and transverse and flat land, are limited by topography and space, are short in construction land, are developed in a digging and filling manner in many areas, and form a large amount of loess high filling projects. The loess high filling engineering is a special geologic body consisting of three surfaces, two bodies and two water bodies, the original foundation body in the two bodies has large-thickness collapsible loess, and the filling material of the filling body is mostly collapsible loess excavated in situ. The collapsible loess has special properties such as water sensitivity, macroporosity, structural property and the like, generally has higher strength under the condition of natural water content, and once the collapsible loess is soaked by water, the soil structure is rapidly destroyed, the bearing capacity is rapidly reduced, and obvious additional subsidence is generated, so that a building (structure) on a loess field is cracked or even destroyed. For this reason, engineering measures are required to eliminate the sagging deformation of the foundation. In the existing high-fill sites, the special investigation and design are adopted, and the orderly high-fill engineering of filling soil through layered rolling or dynamic compaction treatment is adopted, so that the filling soil has a compact structure, and the collapsibility is basically eliminated; the other type is that the special investigation and design are not carried out, the filling soil is not subjected to layered rolling or dynamic compaction treatment, the filling soil structure is loose, the collapsibility is not eliminated, and larger collapsibility deformation can be generated once the filling soil is immersed, so that the foundation reinforcement treatment is required to be carried out again before engineering construction, and the uniformity, compactness and stability of the foundation are ensured.
The dynamic compaction method has the advantages of simple construction, high efficiency, short construction period and the like, and is widely applied to the treatment of loess filling sites. The quality of the dynamic compaction treatment effect is closely related to the water content of foundation soil, in northwest arid regions, the water content of loess as a loess filling source is usually low (the natural water content is often lower than 8%), the collapsible loess foundation is treated by adopting the dynamic compaction method according to the specification of the standard of the Chinese engineering construction standardization institute (CECS 279-2010), the natural water content of soil is preferably lower than the plastic limit water content by 1% -3%, and the natural water content of soil is preferably humidified to be close to the optimal water content when the natural water content of soil is lower than 10% in a soil layer to be compacted. Therefore, in order to ensure the dynamic compaction treatment effect, the loess with low water content needs to be humidified before the dynamic compaction construction. The unordered high-fill site in northwest arid areas has low water content, and the fill is not compacted (rammed), so that the internal structure is loose, and cracks and cavities develop. When the water injection holes are adopted to humidify the low water content filling soil, water infiltrates downwards along the dominant channels such as cracks and holes, and the areas far away from the dominant channels are free from water infiltration, so that local water content is saturated, and the local water content is still lower, thereby being unfavorable for dynamic compaction treatment. Therefore, development of a combined construction method of pre-ramming and humidifying dynamic compaction of unordered high-fill sites is needed to solve the problems of uneven water injection humidifying, poor dynamic compaction treatment effect and the like of unordered fill sites caused by crack and cavity development.
Chinese patent document publication No. CN113463609a, publication No. 2021, 4, 6 discloses a method for treating deep saturated soft soil foundation by "relay type" dynamic compaction displacement treatment. S100-construction preparation is carried out, geological conditions, construction conditions, the range and thickness of saturated weak soil to be replaced and the groundwater level of a site are known in detail, and a crane and a rammer which can meet the depth of dynamic compaction replacement are arranged; a replacement material is prepared that meets the requirements. S200-site leveling and paving a 1.5-2.0 m thick cushion layer, wherein the cushion layer material is the same as the dynamic compaction replacement material, and the construction requirements of construction equipment are met. S300, performing a single-point dynamic compaction replacement pier ramming test. S400-performing dynamic compaction replacement pier construction according to construction parameters determined by the single-point dynamic compaction replacement pier test. The problems that the expected treatment effect is difficult to achieve and the cost is huge by adopting the traditional foundation treatment method are solved, but the document still does not solve the problems of uneven water injection humidification and poor dynamic compaction treatment effect caused by crack and cavity development of a disordered filling site.
Disclosure of Invention
The invention provides a combined construction method of pre-ramming and humidifying dynamic compaction of a disordered high-fill site, which aims to solve the problems of uneven humidifying and poor reinforcing effect in the prior art when the dynamic compaction foundation of the disordered high-fill site is treated.
Therefore, the invention provides a combined construction method of pre-ramming and humidifying dynamic compaction of a disordered high-fill site, which comprises the following steps:
1) Detecting cracks and holes in a target site;
2) Pre-ramming to eliminate cracks and hollows in a target site;
3) Injecting water into the pre-compacted target site for humidification;
4) And carrying out dynamic compaction construction on the humidified target site until the target site reaches the requirement.
Preferably, the step 1) includes the steps of:
101 Cleaning and leveling the target site to a flat site;
102 High-density electrical measuring lines are arranged on a flat field;
103 Connecting the high-density electrical measuring line with the monitoring electrode, and measuring the resistivity data of the target area;
104 Interpreting the resistivity profile;
105 Determining the distribution range and depth of cracks and cavities in the filling soil of the target area according to the resistivity profile;
106 Checking the crack and void area of step 105).
Preferably, the step 2) includes the steps of:
201 Setting a tamping point along the position right above the crack and the cavity, and determining the effective reinforcement depth of dynamic compaction according to the range and depth of the detected crack and cavity;
202 Setting a tamping point in the horizontal direction range of the crack and the cavity range, requiring the tamping point to be located right above the crack and the cavity, tamping the tamping point, and stopping tamping after the tamping settlement reaches the tamping stopping standard, and filling the tamping pit;
203 Full ramming is carried out on the surface layer loose soil in the ramming range in the step 202), and the field after full ramming is cleaned and leveled;
204 Detecting the range of the crack and the cavity again, comparing the resistivity changes at the same depth in the filled soil before and after the compaction, judging the elimination condition of the compaction construction on the crack and the cavity, and repeating the steps 201) to 203) until all the crack and the cavity are eliminated if the crack and the cavity are not eliminated.
Preferably, the step 3) includes the steps of:
301 Determining humidification parameters of the pre-rammed target site;
302 Determining a humidification depth of the pre-rammed target site;
303 Determining water injection hole parameters of the pre-compacted target site;
304 Determining single-hole water injection quantity of the pre-compacted target site;
305 Drilling a water injection hole in the pre-rammed target site;
306 Monitoring step 305) the water content of the soil of the target site;
307 Water is injected into the water injection hole;
308 And stopping water injection when the water content in the water injection hole is monitored to reach the target range.
Preferably, the step 102) is to lay out the high-density electrical measuring line on the flat field by the following steps: a plurality of equidistant and parallel high-density electrical measuring lines are respectively distributed on a flat field along the longitudinal direction and the transverse direction, the longitudinal and the transverse high-density electrical measuring lines form a square measuring network, equidistant high-density electrical measuring points are arranged on the high-density electrical measuring lines, measuring electrodes are vertically inserted into soil at the high-density electrical measuring points, and the measuring electrodes are connected with a position detector through an electrode conversion device.
Preferably, the step 103) measures the resistivity data of the target area in the form of a temperature nano device, and the isolation coefficient is 1-10 during measurement.
Preferably, the specific method for determining the distribution range and depth of the cracks and the cavities in the filling of the target area according to the resistivity profile in step 105) is as follows: setting the average value of the soil filling resistivity measured values of the crack-free and cavity-free distribution areas as a resistivity threshold, searching an image closed area with the resistivity value larger than the resistivity threshold on a resistivity profile of each detected area, wherein when the image closed area with the resistivity value larger than the resistivity threshold exists, the image closed area is a crack-cavity undetermined layer on the detected area, and when the image closed area with the resistivity value larger than the resistivity threshold does not exist, the detected area is free from cracks or cavities.
Preferably, the step 106) is implemented by checking the crack and the cavity area in step 105), which is as follows: and drilling and static sounding are carried out on the crack and cavity areas, the drilling and static sounding are in a filling body, the maximum depth of the drilling and static sounding needs to penetrate through the top surface of the original foundation to enter the original foundation, and exceeds the effective detection depth of a high-density electric method, when the phenomenon that slurry in a hole uniformly drops when sudden drill falling or water drilling occurs in the drilling process, and when the static sounding resistance at the adjacent position and the depth of a target range is reduced to a target range value, the crack or cavity development exists at the position, otherwise, the crack or cavity development does not exist.
Preferably, the method for determining the humidification parameters of the target site after pre-ramming in step 301) is as follows: taking original soil samples of a target site after pre-ramming before construction, wherein the sampling interval is 0.5 m-1.0 m during sampling, and measuring the natural water content w of soil bodies with different depths below a ramming surface 0 Maximum dry density ρ d And an optimal water content w op And calculating the weighted average value w of the natural water content of the soil body at different depths below the ramming surface by adopting a thickness weighting method.
Preferably, the method of 302) determining the humidification depth of the pre-rammed target site is as follows:according to the natural water content w of the soil body in the step 301) 0 The humidification depth is judged in the required reinforcement depth range, and the judgment mode is as follows: when the natural water content w of the soil body 0 When the humidity is lower than 8%, the soil body needs to be humidified; when the natural water content w of the soil body 0 When the water content is lower than 10%, the soil body needs to be humidified to the optimal water content.
The invention has the beneficial effects that:
1. the invention provides a combined construction method of pre-ramming and humidifying dynamic compaction of a disordered high-fill site, which comprises the following steps: 1) Detecting cracks and holes in a target site; 2) Pre-ramming to eliminate cracks and hollows in a target site; 3) Injecting water into the pre-compacted target site for humidification; 4) Carrying out dynamic compaction construction on the humidified target site until the target site reaches the requirement; the crack and the cavity are pre-rammed and eliminated and then humidified, so that the problems of ground collapse, water falling hole formed by water loss along the crack and uneven humidification caused by water injection humidification can be solved; the invention has high practical value, is convenient for popularization and application, solves the problems of large processing difficulty, long construction period and high post-construction sedimentation requirement of unordered high-fill sites, has the advantages of good processing effect, high construction speed, small residual sedimentation and the like, and has better application prospect.
2. According to the combined construction method for pre-ramming and humidifying dynamic compaction of the unordered high-fill site, the high-density electrical measuring line is distributed on the flat site, the high-density electrical measuring line is connected with the monitoring electrode, and the resistivity data of the target area is measured; interpreting the resistivity profile; determining the distribution range and depth of cracks and cavities in the filling of the target area according to the resistivity profile; finally, checking the crack and the cavity area; the crack and cavity distribution condition in the field can be timely and accurately generated.
3. According to the combined construction method for pre-ramming and humidifying dynamic ramming of the unordered high-fill site, when the parameters of the water injection holes are determined, the water injection holes are arranged in a combined mode of deep water injection holes and shallow water injection holes, wherein the deep water injection holes are used for humidifying deep stratum, the shallow water injection holes are used for humidifying shallow stratum, namely, the water injection humidifying mode of combining the deep and shallow holes is adopted, so that the problem of uneven water injection humidifying caused by uneven upper stratum and lower stratum is avoided.
Drawings
The present invention will be described in further detail with reference to the accompanying drawings.
FIG. 1 is a schematic diagram of a high density electrical survey line;
FIG. 2 is a schematic illustration of a high density electrical method for detecting cracks and voids;
FIG. 3 is a horizontal schematic view of tamper points during crack and cavity pre-tamper;
FIG. 4 is a schematic view of the depth and extent of cracks and voids;
FIG. 5 is a schematic view of the horizontal distribution of water injection holes and monitor holes;
FIG. 6 is a schematic longitudinal cross-sectional view of a water injection hole and a monitor hole;
FIG. 7 is a schematic diagram of the tamper point layout for the humidified dynamic compaction construction of the present invention.
Reference numerals illustrate: 1. a high-density electrical measurement line; 2. measuring points by a high-density electrical method; 3. a void boundary line; 4. a filling body; 5. the top surface of the original foundation; 6. an original foundation; 7. cracking; 8. a cavity; 9. exploring the drill hole; 10. static cone penetration equipment; 11. pre-tamping the first tamping point; 12. pre-tamping the second tamping point; 13. pre-tamping the third tamping point; 14. pre-tamping the tamping points for the fourth time; 15. a rammer; 16. a rammer; 17-1, deep water injection holes; 17-2, shallow water injection holes; 18. a water content monitoring hole; 19. a soil moisture meter; 20. a cable; 21. a data acquisition system; 22. bean gravel; 23. humidifying and tamping the first tamping point; 24. humidifying the tamping points for the second time; 25. and (5) humidifying the ramming point for the third time.
Detailed Description
Example 1:
a method for constructing a pre-ramming and humidifying dynamic compaction combination of a disordered high-fill site comprises the following steps:
1) Detecting cracks and holes in a target site;
2) Pre-ramming to eliminate cracks and hollows in a target site;
3) Injecting water into the pre-compacted target site for humidification;
4) And carrying out dynamic compaction construction on the humidified target site until the target site reaches the requirement.
The invention can solve the problems of ground collapse, water falling hole formed by water loss along the cracks and uneven humidification caused by water injection humidification by pre-ramming the cracks and the cavities for elimination and then humidification; the invention has high practical value, is convenient for popularization and application, solves the problems of large processing difficulty, long construction period and high post-construction sedimentation requirement of unordered high-fill sites, has the advantages of good processing effect, high construction speed, small residual sedimentation and the like, and has better application prospect.
Example 2:
on the basis of embodiment 1, said step 1) comprises the steps of:
101 Cleaning and leveling the target site to a flat site;
specifically, construction waste, weed roots and wastes in the construction site are removed, and the construction waste, weed roots and wastes are pushed and flattened to form a flat site.
102 High-density electrical measuring lines are arranged on a flat field;
preferably, as shown in fig. 1, the method of laying out the high-density electrical measuring line 1 on the flat field in step 102) is as follows: a plurality of equidistant and parallel high-density electrical measuring lines 1 are respectively distributed on a flat field along the longitudinal direction and the transverse direction, the longitudinal direction and the transverse direction of the high-density electrical measuring lines form a square measuring network, equidistant high-density electrical measuring points 2 are arranged on the high-density electrical measuring lines, measuring electrodes are vertically inserted into soil at the high-density electrical measuring points, and the measuring electrodes are connected with a position detector through an electrode conversion device.
Specifically, the distance between adjacent high-density electrical measurement lines is 2-4 m, and the distance between adjacent high-density electrical measurement points is 1.0-2.0 m; the measuring electrode is connected to the electrode conversion device through a multi-core cable 20, and the plane coordinates and the elevation of the high-density electrical measuring point are measured by adopting a GPS RTK or a total station and the like. The method can accurately obtain the position information of the high-density electrical measuring point.
103 Connecting the high-density electrical measuring line with the monitoring electrode, and measuring the resistivity data of the target area;
preferably, the step 103) measures the resistivity data of the target area in the form of a temperature nano device, and the isolation coefficient is 1-10 during measurement.
Specifically, a high-density electrical method instrument is adopted to detect the high-fill site. The temperature and the pressure are measured in a form of a temperature and pressure measuring device, the isolation coefficient is 1-10, and cracks and cavities can be identified by ensuring that the detection depth exceeds the thickness and the resolution of the filled soil. And in the measurement process, a plurality of monitoring electrodes connected on the high-density electrical method measuring line are electrified to obtain a plurality of groups of resistivity data corresponding to the region to be measured.
104 Interpreting the resistivity profile;
specifically, the specific method for interpreting the resistivity profile is as follows: and transmitting the multiple groups of resistivity data obtained on each high-density electrical measurement line to a computer (data acquisition system 21), and carrying out inversion analysis processing on each group of resistivity data by the computer, wherein each group of resistivity data can draw a resistivity profile. The inversion analysis processing process is as follows: firstly, removing abnormal points by adopting a denoising technology, correcting preprocessing such as terrain and format conversion, calling the preprocessing into CRT data processing software, then, importing data into RES2DINV for two-dimensional inversion, drawing an inversion result into a contour map by adopting Surfer software, carrying out geological interpretation according to the change characteristics of apparent resistivity values on the contour map and combining the existing investigation data and soil difference points of a field, and finally, drawing a resistivity profile by utilizing Auto-CAD software.
105 Determining the distribution range and depth of cracks and cavities in the filling soil of the target area according to the resistivity profile;
the hidden trouble of holes, cracks and the like is mainly characterized by high resistance, low density, low dielectric constant and the like. Therefore, the average of the fracture-free and void-distributed area fill resistivity measurements is set as the resistivity threshold.
Preferably, the specific method for determining the distribution range and depth of the crack 7 and the cavity 8 in the filling of the target area according to the resistivity profile in the step 105) is as follows: setting the average value of the soil filling resistivity measured values of the crack-free and cavity-free distribution areas as a resistivity threshold, searching an image closed area (high-resistance closed loop) with the resistivity value larger than the resistivity threshold on the resistivity profile of each detected area, wherein when the image closed area with the resistivity value larger than the resistivity threshold exists, the image closed area is a layer to be determined of cracks and cavities on the detected area, and when the image closed area with the resistivity value larger than the resistivity threshold does not exist, the detected area is free of cracks or cavities. Reference numeral 3 in fig. 1 denotes a defined boundary line of the cavity.
106 Checking the crack and void area of step 105).
Preferably, as shown in fig. 2, the step 106) is implemented by checking the crack and the cavity area in step 105), which is as follows: and drilling (or exploratory well or exploratory groove) and static sounding (adopting a survey drilling hole 9) on the crack and cavity area, wherein the drilling and static sounding are arranged in the filling body 4, the maximum depth of the drilling and static sounding needs to penetrate through the top surface 5 of the original foundation 6 and exceed the effective detection depth of a high-density electric method, when the phenomenon of uniform decline of slurry in the hole occurs when the sudden drill falling or water drilling occurs in the drilling process, and when the static sounding resistance at the adjacent position and the depth of a target range is reduced to the value of the target range, the crack or cavity is developed at the position, or else the crack or cavity is not developed.
Example 3:
on the basis of embodiment 2, said step 2) comprises the steps of:
201 Setting a tamping point along the position right above the crack and the cavity, and determining the effective reinforcement depth of dynamic compaction according to the range and depth of the detected crack and cavity;
specifically, as shown in fig. 3 and fig. 4, a tamping point is set along the position right above the development position of the crack and the cavity, the depth H0 and the range of the crack or the cavity are measured according to the step one, the dynamic compaction energy level for tamping the crack and the cavity is eliminated under the condition of no humidification is determined through a site test compaction test or regional experience, the effective reinforcement depth H of the dynamic compaction is determined, and when test data or experience is absent, the effective reinforcement depth h= (1.1-1.2) H0 of the dynamic compaction is required according to the specification of building foundation treatment technology JGJ 79-2012.
202 Setting a tamping point in the horizontal direction range of the crack and the cavity range, requiring the tamping point to be located right above the crack and the cavity, tamping the tamping point, and stopping tamping after the tamping settlement reaches the tamping stopping standard, and filling the tamping pit;
in particular, the outermost edge points of the crack or hole are required to be within the tamper range of the ram with tamper point spacing no greater than 3.5 times the diameter of the ram.
Preferably, when the tamping is performed on the tamping points (using the tamping machine 15), the first time is separated by a point for tamping (see the tamping points 11 in the first time), the first time is filled with gaps (see the tamping points 12 in the second time), the third time is filled with gaps (see the tamping points 13 in the third time), the fourth time is filled with gaps along the three previous times (see the tamping points 14 in the fourth time) on the development range line of the cavity after the point is completely filled, and finally, the low-energy full tamping is performed to achieve the condition that the hammers overlap each other, and the overlapping of the full tamping is not smaller than 1/4 of the diameter of the tamping hammer 16. And (3) in each dynamic compaction construction process, when the compaction and settlement amount of the last two strokes reaches the compaction stopping standard, filling up the compaction pit by using a bulldozer.
Preferably, the tamper stopping standard is determined by on-site tamper testing, and when test data or experience is absent, the tamper stopping standard is executed according to the dynamic compaction energy level E according to the following requirements: when E is less than 4000 kN.m, the final two ramming settlement is less than 5cm; when E is more than or equal to 4000 kN.m and less than 6000kN.m, the final two-impact ramming settlement is less than 10cm; when E is more than or equal to 6000kN.m and less than 8000 kN.m, the final two-impact ramming settlement is less than 15cm; when E is less than 12000 kN.m and is more than 8000 kN.m, the final two-impact ramming settlement is less than 20cm; when E is more than or equal to 12000 kN.m, the final two ramming settlement is less than 25cm.
203 Full ramming is carried out on the surface layer loose soil in the ramming range in the step 202), and the field after full ramming is cleaned and leveled;
specifically, after the spot ramming is finished, the surface layer loosens soil in the dynamic ramming range by adopting the dynamic ramming energy level of 1000 kN.m-2000 kN.m, and the site is cleaned and leveled.
204 Detecting the range of the crack and the cavity again, comparing the resistivity changes at the same depth in the filled soil before and after the compaction, judging the elimination condition of the compaction construction on the crack and the cavity, and repeating the steps 201) to 203) until all the crack and the cavity are eliminated if the crack and the cavity are not eliminated.
Specifically, the crack and cavity development area is detected again by adopting a high-density electrical method after pre-tamping according to the same measuring line and measuring point positions before pre-tamping.
Example 4:
on the basis of embodiment 3, said step 3) comprises the steps of:
301 Determining humidification parameters of the pre-rammed target site;
preferably, the method for determining the humidification parameters of the target site after pre-ramming in step 301) is as follows: taking original soil samples of a target site after pre-ramming before construction, wherein the sampling interval is 0.5 m-1.0 m during sampling, and measuring the natural water content w of soil bodies with different depths below a ramming surface 0 Maximum dry density ρ d And an optimal water content w op And calculating the weighted average value w of the natural water content of the soil body at different depths below the ramming surface by adopting a thickness weighting method.
302 Determining a humidification depth of the pre-rammed target site;
preferably, the method of 302) determining the humidification depth of the pre-rammed target site is as follows: according to the natural water content w of the soil body in the step 301) 0 The humidification depth is judged in the required reinforcement depth range, and the judgment mode is as follows: when the natural water content w of the soil body 0 When the humidity is lower than 8%, the soil body needs to be humidified; when the natural water content w of the soil body 0 When the water content is lower than 10%, the soil body needs to be humidified to the optimal water content.
303 Determining water injection hole parameters of the pre-compacted target site;
preferably, the water injection holes are arranged in a combination of the deep water injection holes 17-1 and the shallow water injection holes 17-2, wherein the deep water injection holes are used for humidifying the deep stratum, and the shallow water injection holes are used for humidifying the shallow stratum.
Preferably, the water injection holes adopt 2 kinds of hole depths, and the 2 kinds of hole depths are deep water injection hole depths and shallow water injection hole depths;
the depth of the deep water injection hole is determined according to the foundation reinforcement depth H, and the vertical permeability K y Greater than horizontal penetration K x The depth H of the deep water injection hole is preferably (H-2) m to (H-4) m; when the vertical permeability Ky of the filled soil is smaller than or equal to the horizontal permeability Kx, the depth h of the water injection hole is preferably equal to the reinforcingThe depth (H-1) m to (H-2) m;
the depth of the shallow water injection hole is 1/2-2/3 of that of the deep water injection hole;
the construction convenience is ensured by adopting the deep water injection hole depth and the shallow water injection hole depth of 2 kinds of holes.
Preferably, the water injection Kong Caiyong is arranged in a regular triangle or square shape, the diameter is 130mm-160mm, and the interval is 1.0m-2.0m. The water injection effect is better.
304 Determining single-hole water injection quantity of the pre-compacted target site;
specifically, determining a single-hole water injection rate: according to the total water injection hole quantity in the field, determining the treatment area of a single water injection hole and the thickness of a humidifying soil layer, wherein the water injection quantity of the single water injection hole can be calculated according to the following formula:
wherein: q is single hole water injection quantity (m 3 )；w op The optimal water content (%) of the natural soil is in the depth range of the to-be-humidified filling soil;the water content of natural soil is weighted average (%) in the depth range of the to-be-humidified filling soil; />In the range of the depth of the to-be-humidified filling soil, the dry density of the natural soil is weighted and averaged (g/cm 3 ) The method comprises the steps of carrying out a first treatment on the surface of the A is the single-hole processing area (m 2 ) The method comprises the steps of carrying out a first treatment on the surface of the h is the thickness (m) of the single Kong Ni humidified soil layer.
305 Drilling a water injection hole in the pre-rammed target site;
preferably, the water injection holes are square or regular triangle holes.
Preferably, the hole spacing is determined based on the single hole waterflooding humidification range. The empty space is 0.8 m-2.0m.
Preferably, the water injection Kong Caiyong is drilled into the holes; and the construction efficiency is improved.
Preferably, a silt field with the water content lower than 8% is punched into holes (hammering immersed tube holes); the collapse of the hole can be prevented.
Preferably, sand gravel (bean gravel 22) or coarse sand is poured into the water injection holes after the water injection holes are formed; the water injection hole can be prevented from collapsing.
306 Monitoring step 305) the water content of the soil of the target site;
as shown in fig. 5 and 6, specifically, 3 types of water content monitoring points (water content monitoring holes 18) are arranged at the centroid positions between adjacent water injection holes, at the 1/2 positions of the connecting lines of the centroid and the water injection holes and at the midpoints of the connecting lines of the adjacent water injection holes, the water content is monitored by adopting a soil moisture meter 19, each monitoring point starts from the depth of 1m below the ground, a plurality of measuring points are arranged along the same vertical direction, the vertical distance between the measuring points is preferably 1.0m-2.0m, and the maximum monitoring depth exceeds the designed maximum humidification depth by not less than 1.0m. The soil moisture meter is installed in a soil layer through a drill hole, and is connected with an automatic monitoring system after the soil moisture meter is installed, and the change of the moisture content in the soil is observed every 1-3 hours.
307 Water is injected into the water injection hole;
specifically, after the construction of the water injection hole is finished, a plurality of water injection holes are divided into a construction district and a cofferdam is built for conveniently injecting water into the water injection hole. And calculating the total water injection quantity Q=nq required by each construction district according to the water injection hole quantity n of the district in the cofferdam. In order to ensure the uniformity of the water content of the filling soil in the depth range to be humidified, the local water content is prevented from being too high or too low, the water injection process adopts a small quantity of multiple times, the water injection times are preferably 3-5 times, the time interval between each water injection is 1 d-2 d, and the water is ensured to be permeated from the water injection holes to the periphery.
308 And stopping water injection when the water content in the water injection hole is monitored to reach the target range.
Specifically, the target range is [ w op -3％,w op +3％]When the water content monitoring point set in step 306 observes that the water content variation range of the filling soil with different depths is [ w ] op -3％,w op +3％]And when the humidification requirement is met, the subsequent dynamic compaction construction can be performed.
Example 5:
on the basis of the embodiment 4, the step 4) is to perform dynamic compaction construction on the humidified target site until the target site reaches the requirement.
Specifically, when the filling and humidification requirements are met, the dynamic compaction energy level is determined through site test compaction or regional experience, and when test data or experience is absent, the dynamic compaction energy level can be determined according to the technical Specification for building foundation treatment JGJ 79-2012. As shown in FIG. 7, the humidifying and dynamic compaction construction of the disordered high backfill field is preferably performed in a four-pass mode: (1) first pass point (first pass tamper point 23 of humidification tamper): the tamping points are arranged in a square shape, and the distance between the tamping points can be 2.5-3.5 times of the diameter of the rammer; (2) second pass point (second tamper point 24 of tamper for humidification): inserting a tamping point at the centroid of the square; (3) third pass (third pass tamper point 25 of tamper with moisture): the diamond arrangement is that the center positions of four adjacent main tamping points are arranged in the first pass and the second pass; (4) fourth pass: the number of the ramming is 2, and the number of the ramming is not less than 1/2 of the ramming (ramming diameter). The stopping criteria are performed as per step 202, or excessive bulging or lateral displacement around the tamper pit, or excessive tamper pit depth, and difficulty in lifting the hammer.
In the description of the present invention, it should be understood that, if any, the terms "upper," "lower," and the like indicate an orientation or a positional relationship based on that shown in the drawings, rather than indicate or imply that the devices or elements being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus the terms describing the positional relationship in the drawings are merely for illustration and are not to be construed as limiting the present invention.
The foregoing examples are merely illustrative of the present invention and are not intended to limit the scope of the present invention, and all designs that are the same or similar to the present invention are within the scope of the present invention.
Claims (10)
1. A method for constructing a pre-ramming and humidifying dynamic compaction combination of a disordered high-fill site is characterized by comprising the following steps: the method comprises the following steps:
1) Detecting cracks and holes in a target site;
2) Pre-ramming to eliminate cracks and hollows in a target site;
3) Injecting water into the pre-compacted target site for humidification;
4) And carrying out dynamic compaction construction on the humidified target site until the target site reaches the requirement.
2. The method for combined construction of pre-ramming and humidifying dynamic ramming of unordered high-fill sites as claimed in claim 1, wherein the method comprises the following steps: the step 1) comprises the following steps:
101 Cleaning and leveling the target site to a flat site;
102 High-density electrical measuring lines are arranged on a flat field;
103 Connecting the high-density electrical measuring line with the monitoring electrode, and measuring the resistivity data of the target area;
104 Interpreting the resistivity profile;
105 Determining the distribution range and depth of cracks and cavities in the filling soil of the target area according to the resistivity profile;
106 Checking the crack and void area of step 105).
3. The method for combined construction of pre-ramming and humidifying dynamic ramming of unordered high-fill sites as claimed in claim 2, which is characterized in that: said step 2) comprises the steps of:
201 Setting a tamping point along the position right above the crack and the cavity, and determining the effective reinforcement depth of dynamic compaction according to the range and depth of the detected crack and cavity;
202 Setting a tamping point in the horizontal direction range of the crack and the cavity range, requiring the tamping point to be located right above the crack and the cavity, tamping the tamping point, and stopping tamping after the tamping settlement reaches the tamping stopping standard, and filling the tamping pit;
203 Full ramming is carried out on the surface layer loose soil in the ramming range in the step 202), and the field after full ramming is cleaned and leveled;
204 Detecting the range of the crack and the cavity again, comparing the resistivity changes at the same depth in the filled soil before and after the compaction, judging the elimination condition of the compaction construction on the crack and the cavity, and repeating the steps 201) to 203) until all the crack and the cavity are eliminated if the crack and the cavity are not eliminated.
4. The method for combined construction of pre-ramming and humidifying dynamic ramming of unordered high-fill sites as claimed in claim 3, wherein the method comprises the following steps: said step 3) comprises the steps of:
301 Determining humidification parameters of the pre-rammed target site;
302 Determining a humidification depth of the pre-rammed target site;
303 Determining water injection hole parameters of the pre-compacted target site;
304 Determining single-hole water injection quantity of the pre-compacted target site;
305 Drilling a water injection hole in the pre-rammed target site;
306 Monitoring step 305) the water content of the soil of the target site;
307 Water is injected into the water injection hole;
308 And stopping water injection when the water content in the water injection hole is monitored to reach the target range.
5. The method for combined construction of pre-ramming and humidifying dynamic ramming of unordered high-fill sites as claimed in claim 2, which is characterized in that: the step 102) is to lay out the high-density electrical measuring line on the flat field by the following steps: a plurality of equidistant and parallel high-density electrical measuring lines are respectively distributed on a flat field along the longitudinal direction and the transverse direction, the longitudinal and the transverse high-density electrical measuring lines form a square measuring network, equidistant high-density electrical measuring points are arranged on the high-density electrical measuring lines, measuring electrodes are vertically inserted into soil at the high-density electrical measuring points, and the measuring electrodes are connected with a position detector through an electrode conversion device.
6. The method for combined construction of pre-ramming and humidifying dynamic ramming of unordered high-fill sites as claimed in claim 2, which is characterized in that: step 103) adopts a temperature nano device to measure the resistivity data of the target area, and the isolation coefficient is 1-10 during measurement.
7. The method for combined construction of pre-ramming and humidifying dynamic ramming of unordered high-fill sites as claimed in claim 2, which is characterized in that: step 105) determining the distribution range and depth of cracks and cavities in the filling soil of the target area according to the resistivity profile, wherein the specific method comprises the following steps: setting the average value of the soil filling resistivity measured values of the crack-free and cavity-free distribution areas as a resistivity threshold, searching an image closed area with the resistivity value larger than the resistivity threshold on a resistivity profile of each detected area, wherein when the image closed area with the resistivity value larger than the resistivity threshold exists, the image closed area is a crack-cavity undetermined layer on the detected area, and when the image closed area with the resistivity value larger than the resistivity threshold does not exist, the detected area is free from cracks or cavities.
8. The method for combined construction of pre-ramming and humidifying dynamic ramming of unordered high-fill sites as claimed in claim 2, which is characterized in that: the step 106) is to test the crack and cavity area in the step 105) as follows: and drilling and static sounding are carried out on the crack and cavity areas, the drilling and static sounding are in a filling body, the maximum depth of the drilling and static sounding needs to penetrate through the top surface of the original foundation to enter the original foundation, and exceeds the effective detection depth of a high-density electric method, when the phenomenon that slurry in a hole uniformly drops when sudden drill falling or water drilling occurs in the drilling process, and when the static sounding resistance at the adjacent position and the depth of a target range is reduced to a target range value, the crack or cavity development exists at the position, otherwise, the crack or cavity development does not exist.
9. The method for combined construction of pre-ramming and humidifying dynamic ramming of unordered high-fill sites as claimed in claim 4, which is characterized in that: the method for determining the humidification parameters of the pre-compacted target site in the step 301) is as follows: taking original soil samples of a target site after pre-ramming before construction, wherein the sampling interval is 0.5 m-1.0 m during sampling, and measuring the natural water content w of soil bodies with different depths below a ramming surface 0 Maximum dry density ρ d And an optimal water content w op And calculating the weighted average value w of the natural water content of the soil body at different depths below the ramming surface by adopting a thickness weighting method.
10. The unordered high fill site pre-formulation of claim 9The method for constructing the dynamic compaction by ramming and humidifying is characterized by comprising the following steps of: the 302) the method for determining the humidification depth of the target site after pre-ramming comprises the following steps: according to the natural water content w of the soil body in the step 301) 0 The humidification depth is judged in the required reinforcement depth range, and the judgment mode is as follows: when the natural water content w of the soil body 0 When the humidity is lower than 8%, the soil body needs to be humidified; when the natural water content w of the soil body 0 When the water content is lower than 10%, the soil body needs to be humidified to the optimal water content.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117589632A (en) * | 2024-01-18 | 2024-02-23 | 山西金宝岛基础工程有限公司 | Method for testing water content in foundation water injection humidifying process through dynamic compaction |
| CN117626934A (en) * | 2024-01-09 | 2024-03-01 | 中铁北京工程局集团有限公司 | Dynamic compaction construction process for low-moisture-content collapsible soil |
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- 2023-07-12 CN CN202310856967.9A patent/CN117051809A/en active Pending
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117626934A (en) * | 2024-01-09 | 2024-03-01 | 中铁北京工程局集团有限公司 | Dynamic compaction construction process for low-moisture-content collapsible soil |
| CN117589632A (en) * | 2024-01-18 | 2024-02-23 | 山西金宝岛基础工程有限公司 | Method for testing water content in foundation water injection humidifying process through dynamic compaction |
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