Method for reinforcing vacuum preloading soft foundation by using high-pressure sand blasting pile

Abstract

The invention discloses a method for reinforcing a vacuum preloading soft foundation by using a high-pressure sand blasting pile, which comprises the following steps: step 1, firstly leveling a site, then exploring the soft foundation, ascertaining a geologic structure in a soft soil foundation to be treated, and then paving a lower drainage cushion layer; step 2, measuring a discharge point, and placing a pile forming system in place; thirdly, a pile forming system is used, a hole is drilled in the pile forming point position, then high-pressure rotary jet grouting pile forming construction is conducted, and a high-pressure sand jet pile is constructed; fourthly, an upper drainage cushion layer is paved, a filter pipe is arranged in the drainage cushion layer, geotechnical cloth and a sealing film are paved on the drainage cushion layer, and the periphery of the geotechnical cloth and the sealing film are embedded into the impermeable stratum to seal the drainage cushion layer; 5, the filter pipe extends out of the geotechnical cloth and the sealing film through a film outlet device and is connected to a vacuumizing device; and sixthly, the vacuumizing device is started, and vacuum preloading drainage is conducted on the soft soil foundation.

Description

Technical Field

[0001] The invention belongs to the technical field of soft soil foundation reinforcement, and in particular relates to a method for vacuum preloading soft soil foundation reinforcement by using high-pressure jet sand piles. Background Art

[0002] In the new era, as my country's economic construction has increased its influence in the international environment, the construction of super-large-scale buildings, intelligent ports, docks and other projects has developed unprecedentedly. In the process of engineering construction, the reinforcement of soft soil foundation is an important factor affecting the comprehensive construction quality of engineering construction. Since soft soil foundation has the characteristics of high water content and poor bearing capacity, if it cannot be scientifically and reasonably managed, it will cause safety risks to varying degrees.

[0003] At present, my country has made some achievements in the practical application and theoretical research of soft foundation reinforcement, such as high-pressure rotary jet pile reinforcement method, drainage consolidation method, dynamic tamping (replacement) method, etc. Various methods have their own advantages and disadvantages in terms of applicable soil layers, efficiency, reinforcement effects, etc. For example, the high-pressure rotary jet pile reinforcement method uses a high-pressure rotating nozzle to spray cement slurry into the soil layer and mix it with the soil to form a cement reinforced pile body. The construction occupies a small area, has low vibration and low noise, but has disadvantages such as environmental pollution, high cost and small scope of application; the drainage consolidation method has the advantages of short construction period and obvious reinforcement effect, but the process is complicated, the cost is high, the preloading effect is subject to certain limitations, and the reinforcement depth is limited. The preloading effect is better when the silt layer thickness is less than 8m. When there is a sand layer in the silt, a sealing wall needs to be added around it.

[0004] Therefore, there are still many problems and challenges in the application and development of soft foundation reinforcement technology. The research on new soft foundation reinforcement technology has a long way to go. In order to seek a soft foundation reinforcement method that can quickly and efficiently improve the physical and mechanical properties of soft soil layers, a method of vacuum preloading soft foundation reinforcement using high-pressure jet sand piles is proposed. Summary of the invention

[0005] The present invention mainly aims to overcome the deficiencies of the prior art and provides a method for vacuum preloading soft foundation reinforcement using high pressure jet sand piles.

[0006] The present invention is achieved through the following technical solutions:

[0007] A method for vacuum preloading soft foundation reinforcement using high-pressure jet sand piles comprises the following steps:

[0008] Step 1: First, the site is leveled, then soft foundation exploration is carried out to find out the geological structure of the soft soil foundation to be treated, and then the drainage cushion layer of the lower layer is laid;

[0009] Step 2: measure the placement points and put the pile system in place;

[0010] Step 3: Use the pile-forming system to first drill holes at the pile-forming points, and then perform high-pressure jetting pile construction to construct high-pressure jet sand piles;

[0011] The pile-forming effect of the pile-forming system in the foundation depends on the strength of each soil layer. After drilling a hole in the soft soil foundation, a vertical sand column will be formed after high-pressure rotary jetting, and the sand column will extend upward to the surface of the soft soil foundation. For the silty soil layer, an expanded sand mound will be formed on the sand column of the high-pressure sand-jetted pile, and the expanded sand mound is a horizontally continuous mound-shaped structure connected to the sand column; for the soil layer with harder soil conditions, a splitting sand belt will be formed on the sand column of the high-pressure sand-jetted pile, and the splitting sand belt is a horizontally extending belt-shaped structure connected to the sand column; in order to achieve a better pile-forming effect, the pile-forming system is controlled during the high-pressure rotary jetting pile construction. For the silty soil layer in the proven soft soil foundation, the sand blasting flow rate and sand blasting pressure of the pile-forming system are increased compared to the hard soil layer. At the same time, the sand blasting residence time of the pile-forming system in the silty soil layer is prolonged, so that a larger expanded sand mound is formed in the silty soil layer;

[0012] Step 4: Spread the upper drainage cushion layer, arrange the filter pipe in the drainage cushion layer, lay the geotextile and the sealing film on the drainage cushion layer and bury the surrounding of the drainage cushion layer in the impermeable stratum to seal the drainage cushion layer;

[0013] Step 5, extending the filter tube out of the geotextile and the sealing film through the film outlet device and connecting them to the vacuum device;

[0014] Step six, turn on the vacuum device to perform vacuum preloading and drainage on the soft soil foundation.

[0015] In the above technical solution, the drainage cushion layer is a thick sand cushion layer.

[0016] In the above technical solution, the pile forming system includes a high-pressure mortar mixing pump, a circulation pipeline and a drilling and spraying machine. The high-pressure mortar mixing pump needs to circulate and stir the mortar. The drilling and spraying machine is connected to the circulation pipeline, and the mortar is provided to the drilling and spraying machine through the circulation pipeline.

[0017] In the above technical solution, the depth of the geotextile and the sealing membrane buried in the impermeable stratum is not less than 50 cm.

[0018] In the above technical solution, a construction process is added between step five and step six, that is, stacking the loading material above the geotextile and the sealing membrane.

[0019] The advantages and beneficial effects of the present invention are:

[0020] (1) The present invention combines the advantages of the high-pressure jet grouting pile reinforcement method and the drainage consolidation method, and combines the high-pressure jet sand pile with the vacuum combined loading preloading to achieve the double reinforcement effect of compaction reinforcement and drainage consolidation for the soft soil foundation, which can effectively improve the physical and mechanical properties of the soft soil foundation and provide effective guarantee for the safety, quality and progress of subsequent engineering construction.

[0021] (2) The high-pressure sand jetting piles of the present invention have the function of improving the bearing capacity of soft foundations. The sand columns, expanded sand piers, and split sand belts improve the soil quality and density of soft soil layers to varying degrees, and can provide an ideal spatial drainage channel for deep soft foundation reinforcement. Under the action of drainage and consolidation, secondary reinforcement of the soft foundation is achieved. In particular, the formation of the split sand belt provides a horizontal drainage channel for the soil layer outside the influence of the high-pressure sand jetting piles, effectively improving the drainage and consolidation effect and process of the soft foundation.

[0022] (3) The present invention is developed for soft foundations with poor soil conditions, and has an obvious reinforcement effect. It can replace or improve extremely soft soil layers more thoroughly, and the reinforcement effect on silty soft soil is more obvious. The introduction of high-pressure jet sand piles solves the problems of traditional high-pressure rotary jet piles that pollute the environment and are high in cost. The combined drainage consolidation method and the dynamic compaction method have the advantages of good reinforcement effect, high construction efficiency, and environmental protection.

[0023] (4) During the high-pressure rotary jet grouting construction, the pile-forming effect of the pile-forming system in the foundation depends on the strength of each soil layer. However, the physical and mechanical properties of the soft soil layer to be treated are unknown, so the pile-forming effect is passive. Therefore, the present invention controls the pile-forming system during the high-pressure rotary jet grouting construction. For the silty soil layer in the proven soft soil foundation, the sandblasting flow rate and sandblasting pressure of the pile-forming system are increased compared to the hard soil layer. At the same time, the sandblasting residence time of the pile-forming system in the silty soil layer is prolonged, so that a larger expanded sand mound is formed in the silty soil layer, thereby being able to carry out targeted and active pile-forming control corresponding to different soil layers, achieving a better pile-forming effect, and thus having a better compaction and reinforcement effect on the soft soil foundation. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 The structure of the present invention is schematically shown Figure 1 .

[0025] Figure 2 The structure of the present invention is schematically shown Figure 2 .

[0026] Figure 3 This is a structural diagram of the pile system.

[0027] In the figure, high-pressure jet sand piles 1, expanded sand piers 11, splitting sand belts 12, sand columns 13, drainage cushion layers 2, pile loading materials 3, pile forming systems 4, high-pressure mortar mixing pumps 41, circulation pipelines 42, drilling and spraying machinery 43, filter tubes 5, vacuum extraction devices 6, geotextiles and sealing membranes 7 are shown.

[0028] For ordinary technicians in this field, other relevant drawings can be obtained based on the above drawings without any creative work. DETAILED DESCRIPTION

[0029] Embodiment 1

[0030] In order to enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention is further described below in conjunction with specific embodiments.

[0031] A method for vacuum preloading soft foundation reinforcement using high-pressure jet sand piles comprises the following steps:

[0032] Step 1: First, the site is leveled, then soft foundation exploration is carried out to find out the geological structure of the soft soil foundation to be treated, and then the drainage cushion layer 2 of the lower layer is laid;

[0033] Wherein, the drainage cushion layer 2 is a thick sand cushion layer;

[0034] Step 2: measure the placement points and put the pile system in place 4;

[0035] The pile forming system 4 includes a high-pressure mortar mixing pump 41, a circulation pipeline 42 and a drilling and spraying machine 43. The high-pressure mortar mixing pump 41 needs to circulate and stir the mortar material to prevent the mortar material from settling and being unable to be sucked into the circulation pipeline 42, thereby affecting the pile forming effect and quality; the drilling and spraying machine 43 is connected to the circulation pipeline 42, and the mortar material is provided to the drilling and spraying machine 43 through the circulation pipeline 42;

[0036] Step 3: using the pile forming system 4, first drilling holes at the pile forming points, and then performing high-pressure jetting pile forming construction to construct high-pressure jet sand piles 1;

[0037] The pile-forming effect of the pile-forming system 4 in the foundation depends on the strength of each soil layer. After drilling, a vertical sand column 13 will be formed on the soft soil foundation after high-pressure rotary spraying. The sand column 13 extends upward to the surface of the soft soil foundation. For silty soil layers, an expanded sand pier 11 will be formed on the sand column 13 of the high-pressure jet sand pile 1. The expanded sand pier 11 is a horizontally continuous pier-shaped structure connected to the sand column 13. The larger the expanded sand pier 11, the better the compaction and reinforcement effect on the soft soil foundation. For soil layers with harder soil conditions, a splitting sand belt 12 will be formed on the sand column 13 of the high-pressure jet sand pile 1. The splitting sand belt 12 is a water-jet sand belt connected to the sand column 13. The horizontally extending strip structure can increase the horizontal contact range between the high-pressure jet sand pile 1 and the soft soil foundation, form a horizontal drainage channel, and improve the horizontal drainage effect; in order to achieve a better pile forming effect, the pile forming system 4 is controlled during the high-pressure jetting pile forming construction, and the sandblasting flow rate and sandblasting pressure of the pile forming system 4 are increased for the muddy soil layer in the proven soft soil foundation compared to the hard soil layer. At the same time, the sandblasting residence time of the pile forming system 4 in the muddy soil layer is prolonged, so that a larger expanded sand pier 11 is formed in the muddy soil layer, thereby improving the compaction and reinforcement effect on the soft soil foundation;

[0038] Step 4: Spread the upper drainage cushion layer 2, arrange the filter tube 5 in the drainage cushion layer 2, lay the geotextile and the sealing film 7 on the drainage cushion layer 2 and bury the surrounding of the geotextile in the impermeable stratum to seal the drainage cushion layer;

[0039] Wherein, the depth of the geotextile and the sealing membrane 7 buried in the impermeable stratum is not less than 50 cm;

[0040] Step 5: The filter tube 5 is extended out of the geotextile and the sealing film 7 through the film outlet device (not shown in the figure) and connected to the vacuum device 6;

[0041] Step 6, start the vacuum device 6 to perform vacuum preloading and drainage on the soft soil foundation;

[0042] After the vacuum device 6 is turned on, the vacuum device 6 vacuumizes the sealed drainage cushion layer 2 through the filter tube 5. Under the action of negative pressure, the water in the soft soil foundation quickly enters the high-pressure jet sand pile 1, and is discharged upward into the drainage cushion layer 2 using the high-pressure jet sand pile 1 as a drainage channel, and finally discharged into the drainage system (not shown in the figure) from the filter tube in the drainage cushion layer 2; specifically, the water in the soil layer within the influence range of the sand column 13 is discharged upward into the drainage cushion layer 2 using the sand column 13 as a vertical drainage channel, and finally discharged into the drainage system (not shown in the figure) from the filter tube in the drainage cushion layer 2; the expansion body Water in the soil layer within the influence range of the sand ditch 11 enters the expanded sand ditch 11, and then enters the sand column 13, and then uses the sand column 13 as a vertical drainage channel to discharge upward into the drainage cushion layer 2, and finally discharges into the drainage system from the filter pipe in the drainage cushion layer 2; water in the soil layer outside the influence range of the sand column 13 and the expanded sand ditch 11 uses the split sand belt 12 as a horizontal drainage channel, and then enters the sand column 13, and then uses the sand column 13 as a vertical drainage channel to discharge upward into the drainage cushion layer 2, and finally discharges into the drainage system from the filter pipe in the drainage cushion layer 2; thereby achieving a more uniform drainage and consolidation effect on the soft soil foundation.

[0043] Embodiment 2

[0044] Based on the first embodiment, this embodiment adds a construction process between step five and step six, that is, stacking the loading material 3 above the geotextile and the sealing membrane 7 in order to quickly squeeze the water in the pores of the soft soil foundation into the high-pressure jet sand pile 1.

[0045] For ease of explanation, spatial relative terms such as "upper", "lower", "left", "right" and the like are used in the embodiments to illustrate the relationship of one element or feature shown in the figure relative to another element or feature. It should be understood that, in addition to the orientation shown in the figure, the spatial terms are intended to include different orientations of the device in use or operation. For example, if the device in the figure is inverted, the element described as being "under" other elements or features will be positioned "on" other elements or features. Therefore, the exemplary term "under" can include both upper and lower orientations. The device can be positioned in other ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used here can be interpreted accordingly.

[0046] Furthermore, relational terms such as “first” and “second” and the like are merely used to distinguish one component from another having the same name, but do not necessarily require or imply any such actual relationship or order between these components.

[0047] The present invention is described above by way of example. It should be noted that, without departing from the core of the present invention, any simple deformation, modification or other equivalent replacement that can be made by those skilled in the art without inventive effort falls within the protection scope of the present invention.

Claims

1. A method for vacuum preloading soft foundation reinforcement using high-pressure jet sand piles, comprising the following steps: Step 1: First, the site is leveled, then soft foundation exploration is carried out to find out the geological structure of the soft soil foundation to be treated, and then the drainage cushion layer of the lower layer is laid; Step 2: measure the placement points and put the pile system in place; Step 3: Use the pile-forming system to first drill holes at the pile-forming points, and then perform high-pressure jetting pile construction to construct high-pressure jet sand piles; The pile-forming effect of the pile-forming system in the foundation depends on the strength of each soil layer. After drilling a hole in the soft soil foundation, a vertical sand column will be formed after high-pressure rotary jetting, and the sand column will extend upward to the surface of the soft soil foundation. For the silty soil layer, an expanded sand mound will be formed on the sand column of the high-pressure sand-jetted pile, and the expanded sand mound is a horizontally continuous mound-shaped structure connected to the sand column; for the soil layer with harder soil conditions, a splitting sand belt will be formed on the sand column of the high-pressure sand-jetted pile, and the splitting sand belt is a horizontally extending belt-shaped structure connected to the sand column; in order to achieve a better pile-forming effect, the pile-forming system is controlled during the high-pressure rotary jetting pile construction. For the silty soil layer in the proven soft soil foundation, the sand blasting flow rate and sand blasting pressure of the pile-forming system are increased compared to the hard soil layer. At the same time, the sand blasting residence time of the pile-forming system in the silty soil layer is prolonged, so that a larger expanded sand mound is formed in the silty soil layer; Step 4: Spread the upper drainage cushion layer, arrange the filter pipe in the drainage cushion layer, lay the geotextile and the sealing film on the drainage cushion layer and bury the surrounding areas in the impermeable stratum to seal the drainage cushion layer; Step 5, extending the filter tube out of the geotextile and the sealing film through the film outlet device and connecting them to the vacuum device; Step six, turn on the vacuum device to perform vacuum preloading and drainage on the soft soil foundation.

2. The method for vacuum preloading soft foundation reinforcement using high pressure jet sand piles according to claim 1 is characterized in that: The drainage cushion layer is a thick sand cushion layer.

3. The method for vacuum preloading soft foundation reinforcement using high pressure jet sand piles according to claim 1 is characterized in that: The pile forming system includes a high-pressure mortar mixing pump, a circulation pipeline and a drilling and spraying machine. The high-pressure mortar mixing pump is required to circulate and stir the mortar material. The drilling and spraying machine is connected to the circulation pipeline, and the mortar material is provided to the drilling and spraying machine through the circulation pipeline.

4. The method for vacuum preloading soft foundation reinforcement using high pressure jet sand piles according to claim 1 is characterized in that: The depth of the geotextile and the sealing membrane buried in the impermeable stratum is not less than 50 cm.

5. The method for vacuum preloading soft foundation reinforcement using high pressure jet sand piles according to claim 1 is characterized in that: A construction process is added between step five and step six, namely, piling up the stockpile above the geotextile and the sealing membrane.

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