TW463011B - Ground base modification: horizontal compaction method - Google Patents

Abstract

This invention of a new construction method aims to intensify the strength and density of soft ground base to prevent liquidizing and large amount of settlement of the structure basing on it. The combination of the following concepts makes the invention totally different from conventional ground base modification method, which is inspired by concepts of vertical loading pre-pressing or solidification of stirring cement paste, and more advantageous-- more reliable, less construction cost, shorter construction schedule, non-pollution: (1) to settle in the earth simultaneously drain vent or drain belt and horizontal pressing hole by which compaction action works to add controllable horizontal effective pressure to the earth in order to intensify the earth density; (2) to put cement paste, air-pressed sand, or chemical foaming body in the hole, with or without putting pipe-like fiber bag according to the feature of strata, to effect horizontal pressure to the earth outside the hole in order to add horizontal effective force of the earth to force pore water draining out of the earth and to compact the earth at pre-pressed density effect of OCR = 2 to 4 for better shear strength and anti-liquidizing.

Description

463011 V. Description of invention ⑴ Preface In recent years, due to the prosperity of the society and the progress of the economy, the buildings of Metropolitan Area X have sprung up everywhere, which has resulted in a significant increase in land use in metropolitan areas. The Taipei Basin is mainly a sedimentary formation of Holocene rivers Layers> Sandy and cohesive soil interlayers are mostly normal compacted (OCR III) soils. 5 If a structure is built on such a layer > When Λ is the biggest in the soil, the previous period is 3c *. (Py) will cause subsidence, especially in the early days of the swamp backfilling of the Lutheran meter area and the recent lands of the Keelung River after loading and deflection. The clay compaction has not been completed, which makes the soil extremely weak. The standard penetration test is about N. ] ~ 4, and most of the buildings in this area are designed for superstructures, and the load is often greater than the soil memory The maximum stress in the medium, even if using a fully-compensated foundation such as -an- sigh meter or poor application of X, will cause the total structural subsidence and differential subsidence to exceed the ambassador's structure rupture and water leakage, so its subsidence problem cannot be inadvertent — as common as The pile foundation or ground 'AS τίΤΤ- improvement and other methods to solve the subsidence problem, but these construction methods due to geological conditions limit the lack of understanding of the construction staff on the geological soil, the construction quality is difficult to control and the effect after construction is difficult to confirm and other factors, the subsidence problem may not be successful In view of this, another method to deal with soil compaction and subsidence is Γ. The lateral compaction site improvement method J has its necessity. 0 Second, the technical content of the method. General soil compaction behavior, theory and Increase the vertical

Page 5 4 630 11 V. Description of the invention (2) Effective Jrf- How heavy is the soil particles to make them more compact and drain the pores between the soil particles-Water gap is discharged Even if the vertical load is removed, the soil particles are also There is only a small amount of springback. The majority of the over-compaction ratio (0 CR) of the weak soil layer in the concept of effective stress in geotechnical engineering is equal to L or slightly greater than 1. Κ 〇 = lateral effective stress between soil particles ( CT 't > The effective vertical stress between soil particles (σ 〆v) and] .5, and the maximum principal stress between the soil masses is related to the total stress angle of the soil mass between the minimum principal stresses. Y Internal friction when using the worst clay The angle (Φ) is 18. The P is analyzed according to the Moore circle (Pole y-: Maximum principal stress, minimum principal stress and 20, σ 〆V — σ [= maximum principal stress, σ-\ yield σ 5: = The minimum principal stress changes a between soils, i.e., the heading pressure makes its force mouth larger, but it does not exceed When σ 'is twice, the soil structure will not be damaged? But it can also produce compaction effect to reach the bearing capacity. The oldest can be increased by four times. The total compaction amount is reduced to 1 / 6- -1/10 before the improvement. Compression index C < r 6 ~ 1 Ox Recompression index C r) Overview of the principle of the three-method method The performance characteristics of the lateral compaction site improvement method can be compared with the traditional method? It highlights the advantages of this method. New concepts and new construction equipment that will keep effective lateral compaction after lateral compaction in the project make construction easier and lower cost) Can be adapted to various stratum conditions and environments J To achieve improvement The current local improvement methods cannot be suitable for all strata The shortcomings of environmental pollution, vibration and the total cost will be generated. The following are the advantages and disadvantages of the previous construction techniques and this construction method.

46301t V. Description of the invention (3) 1. Lattice foundation The most traditional method for building structures in weak strata to solve the problem of insufficient bearing capacity and excessive subsidence. Although this method is reliable, it has the highest cost, long construction period, environmental impact (sludge, noise, vibration) during the construction period, and construction obstacles in difficult-to-treat areas due to future reconstruction. 2. Low pressure grouting consolidation method. The traditional construction method commonly used in weak sandy soil layers is only suitable for formations with good water permeability, k > 1 0 _1cm / s ec, that is, medium coarse sand and sand butterfly formations, not applicable to k < 1 0 -2cm / sec formation, that is, mud and clay formation. Difficult to control during construction Improve the location 'Low reliability, high cost, ineffective control of construction period, causing shortcomings such as site pollution.

1. High pressure spray mixing pile construction method 2 Similar to the C. C · P, J. S · P and other commonly used construction methods in China, all are 180 ~ 4 2 0 kg / cm 2 to spray the cement slurry under high pressure and high speed. Soil layer, crushing a limited range of soil, mixing and consolidating it with cement slurry to form a cylindrical soil body with similar weathering rock strength (q and 15kg / cm2), improving the overall bearing capacity of the weak soil body and reducing subsidence. This construction method is expensive, the construction period is difficult to control, and the cement slurry sprayed under high pressure will cause the nearby ground to swell without destroying the entire structure, and the nearby structure will be completely damaged. 4 630 1 1 V. Description of the invention (4) The traditional method of increasing the bearing capacity and reducing the subsidence of large areas of weak soil. r In the future, it is necessary to cover the excessive subsidence that may occur due to structural heavy objects, and fill it with soil, and then pre-compress the subsidence before removing it. This construction method is only applicable to large-area, long-term construction sites, and cheap earthworks, so it is not suitable for small construction sites, short construction periods, and expensive earth-moving sites. 5. Dynamic compaction method Large area of sandy soil layer, the main purpose is to prevent liquefaction. This method is most suitable. The small area, excessive sedimentation and clay, and the improvement depth of more than 15.0 .0 m are not suitable for dynamic compaction. 6. Shock sand pile compaction method The principle of vibration and water spray is used to make the sand layer nearby to a compact state, prevent liquefaction and reduce subsidence. This method is more expensive than the dynamic compaction method, has a long construction period, and can be improved to a depth of 30 m, but it is only applicable to sandy soil layers and not to mud and clay layers. 7. Improvement method for lateral compaction site This method is mainly to increase the effective lateral pressure in the soil. After the completion of the lateral compaction, the soil will be more compact, and the over-compaction ratio will be increased to 〇 2 ~ 6. The vertical bearing capacity of the soil prevents liquefaction and reduces subsidence. After effective lateral pressure is drilled by a drilling machine, the sandy soil layer with high water permeability is put into a fiber tube bag, and the pressure is set to be less than 3 times the vertical effective soil pressure 4 6 301 1 V. Description of the invention (5)

Quantitative injection of cement slurry, mortar, foam or gas; low-permeability clay formations are directly injected by high-pressure quantitative spraying to form a compression force that produces less than 2 times the vertical effective covering pressure on the surrounding soil, allowing the surrounding soil to enter compaction During the compaction process, the excess pore water is drained from drainage holes or drainage belts to complete the compaction effect in the lateral direction, so as to improve the tightness of the soil layer. This method is not limited by the physical characteristics of the formation (clay, sediment, sand) No noise, vibration, pollution, etc. can be generated during construction. Small machinery and equipment can be used, so it is not limited by the size and space of the base, and can be constructed in the base of the city or the base of completed buildings. The filling agent in this construction method does not contain any chemicals, so it will not produce any ground pollution that affects people and plants, and it will not generate structural obstacles in the ground, which meets the requirements of environmental protection. The length of the construction period can be adjusted by drainage. Band spacing control (the construction period is shortened by 1/3 ~ 1/2 as compared with the traditional method), so the construction period is easy to control. Both the pressure range and the size can be controlled by the equipment, so the compaction quality is easy to manage. The improved land can increase the apparent capacity of weak stratum, reduce subsidence, and prevent liquefaction. The cost of this method is about 1 / 3 ~ 1/2 of the fund, and the overall value is high, which is difficult to achieve by traditional construction methods. 4. Construction steps of the lateral compaction site improvement method When the lateral compaction site improvement method is applied, the main application procedures are as follows:

4 6 301 1 V. Description of the invention (6) I) Survey and analysis of the geological characteristics of the site The method of drilling and sampling is used to understand the standard penetration test (N value) of the site and the physical characteristics of the disturbed soil samples (overall unit weight τ η, porosity Ratio e, water content w, etc.), and the cross compact shear and various mechanical tests to confirm the OCR ratio of the formation. Π) The results of site improvement requirements confirm that structures constructed in weak strata are often loaded by the structure, causing compacted or uneven subsidence of the bearing soil layer, and thus endangering the safety of the structure itself. Therefore, we should start at the beginning of the design. Plan for the need for site improvement of the bearing layer, that is, to which OCR or tightness to improve (can be checked by N value). m) Improvement analysis and construction regulations Based on clear improvement demand standards and the current mechanical status of weak strata, after analysis and evaluation of geotechnical professional experience, price analysis and construction planning are carried out to optimize the construction process and hole locations. Configuration to effectively control construction costs and shorten construction periods to meet economic benefits. IV) Staking out operations ^ Before the construction, inspect the hole position 1, the drainage belt hole position 2, and the horizontally compacted pile hole.

4 630 1 t V. Description of the invention (7) Bit 3 and electronic hydraulic manometer hole 4 are staked out on the working surface according to the planned position. This operation needs to calibrate the building stakeout point at the base and provide its standard reference elevation. (Detailed first picture) V) Drainage holes or drainage belts are drilled with large machinery (if a completed structure is used, a KH-2 drill rig or a larger drill fortress) is used to provide vertical drainage holes 5 and electronically installed Water pressure gauge 6, drain pipe or drainage band 7 in weak soil layer. (Detailed second picture) VI) Horizontal pressure squeeze hole Drilled with lateral pressure squeeze hole 8 to control the pressure up to 180 ~ 420kg / cm2 in the low-permeability clay and sediment layer. The agitating shotcrete machine of the shot will crush a certain amount of mortar liquid to the soil layer next to the shot hole, and the pressure cement slurry sprayed into it will form an effective lateral pressure of 10 in the soil layer; The fiber of the purpose can also be put into the fiber bag 1 1 first, and the mortar, foam or gas 1 2 is poured into the bag to form an effective lateral pressure, which stimulates the excess pore water pressure, and by vertical 1 3, radiation 1 4 Directional drainage, resulting in compaction. (Detailed third picture) W) Monitoring of electronic pore water pressure gauge VI After the completion of the construction, when the cement slurry 17 is poured into the fiber bag under high pressure, the pore water in the formation must be monitored by the electronic water pressure gauge 6 at the same time. Not pressure

4630 1 1 V. Description of the invention (8) The effective overburden pressure should be exceeded, and the surface uplift 18 should be avoided to prevent damage to the stratum structure. (Detailed figure 4) M) Verification of the improvement effect After the completion of the improvement of the lateral compaction method, the mortar is filled with cement mortar in the lateral pressure squeeze hole, and the pore pressure is dissipated by the electronic hydrometer to monitor the pore pressure. Holes to verify whether the standard penetration test (N value '), soil density, water content, mechanical properties, cross-cut shears and other tests of the soil can achieve the purpose of improvement.

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Oil diagram briefly explains the first diagram of the plan layout of the lateral compaction site improvement method. 1. Inspection hole position 2. Drainage hole position 3. Horizontal compaction pile position 4. Electronic hydraulic pressure gauge position 1. 8. Swell bar The figure of the test point is shown with the water metering, pore pressure, drilling water, or row-type pipe layer, straight soil, water, soil, and vertical electricity, sand discharge, and sticking. 5 6 7 5 6 Straight and horizontal horizontal pressure horizontal fiber sand droop ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, ffl 8 9 ο 1 2 3

J square layers of layered soil, sand, sand, viscous gas, or water and water

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Claims (1)

463011 6. Scope of patent application 1 Water treatment method combined with drainage holes (or the soil layer around the drainage holes generates effective lateral pressure to set pressure control to provide pressure degree to improve soil compactness, increase soil shear and reduce subsidence, The functions of feeding, sanding, picking, and functions for the purpose of preventing the liquefaction of the sand layer include: a. Configure the pressure hole 'to fill the cement water hole (or drainage belt) for operation, compaction and compaction; b' Discharge the surface vertically, and speed up the tank with a speed of Λ centimeters. 2. The scope of patent application achieves the purpose of site improvement. Fang Liu m1 lateral compaction site improvement work *, which can be used for vertical pressure or vertical pressure holes. Horizontal configuration, where the pressure hole SIS is used to continuously and smoothly squeeze the soil, and the drainage hole or the degree of drainage is ^. :: discharge to produce a pre-compact effect to improve the soil compaction. The main construction procedure of the lateral compaction site improvement method is as follows: 1) On-site stakeout: Before the construction, the inspection hole location, the drainage belt hole location, the horizontal second compacted pile hole location and the electronic hydraulic pressure gauge hole location are planned. Position advance 2) Drilling of drainage holes or drainage belts: drilling with large machinery (if completed: KH ~ 2 drilling rig or larger drill rig), and placing vertical drainage holes in the holes ( Or drainage belt); Page 14 463011 ~-— _____ 〇 Scope of patent application ^ 3) Installation and installation of electronic water pressure gauge: Large-scale machinery (if it has been completed. The structure is to use KK 2 2 drill rig or larger drill fort) to guide the hole The electronic hydraulic manometer is embedded to a predetermined depth to understand the changes in the horizontal pressure pore water pressure; 4) Lateral pressure pressure holes: Drilling lateral pressure pressure holes and installing pressure equipment; 5) Lateral pressure pressure: In the low-permeability clay and sediment layer, the lateral pressure is controlled by a pressure gauge to control the pressure to 180 ~ 42 0 kg / cm2, and the quantitative spraying can be used to stir the mortar spraying machine to crush the mortar liquid next to the spraying hole. The soil layer can provide effective lateral pressure in the soil layer by the sprayed pressure water. Mud liquid; High-permeability sand layer or special purpose holes can also be put into fiber bags first, using mortar and foam Or gas is poured into the bag to form an effective lateral pressure, which stimulates excess pore water pressure, and discharges water by vertical and radiating directions to produce a compaction effect. 6) Drainage holes and pressure holes can be set separately or in combination. Combining the drainage tape with the pressure hole When starting setting, with drainage holes located outside the pressure bags the fibers' formation of voids by the excessive pressure of the drain in contact with the outer layer of the soil and draining the water when pressurized, to reduce the pore water pressure. Page 15