Construction method for quantitative moisture absorption of collapsible loess foundation

Abstract

The invention relates to the technical field of foundation treatment, in particular to a construction method for quantitative moisture absorption of a collapsible loess foundation. Determining the number, aperture and position of moisture absorption holes according to the total moisture absorption treatment water quantity, and punching to obtain a plurality of moisture absorption holes; a drying agent formula is determined according to the moisture absorption treatment water quantity of at least one soil layer, and a drying device containing a drying agent is placed at the corresponding depth position in each moisture absorption hole; after standing, moisture absorption is completed; the total moisture absorption treatment water amount is obtained according to the volume of the loess foundation, the actual water content of the soil layer at at least one depth position and the optimal water content of the soil layer at the depth position; the soil layer moisture absorption treatment water amount is obtained through the actual water content of the soil layer and the optimal water content of the soil layer. The method has the advantages that the moisture absorption efficiency and effect can be improved, the water content of soil layers with different depths can be more uniformly controlled, the cost is low, the feasibility is high, a required construction device is simple, the operation is convenient, the efficiency is high, the working efficiency can be improved, and the wide application prospect is achieved.

Description

Technical Field

[0001] The invention relates to the technical field of foundation treatment, and in particular to a construction method for quantitative moisture absorption of a collapsible loess foundation. Background Art

[0002] my country's loess region is vast and widely distributed, accounting for 6.6% of my country's total land area. It is concentrated in the middle reaches of the Yellow River Basin, and most of it is collapsible loess. The soil of collapsible loess is relatively soft, loose in structure, and well-developed in pores. Under natural humidity, the compressibility of collapsible loess is small and the strength is high. However, when the collapsible loess is soaked in water, its strength decreases rapidly, the structure is destroyed, the compressibility increases, and significant additional settlement occurs. With the rapid development of the national economy, it is inevitable to carry out construction in complex loess geological areas, and collapsible loess must be treated before it can be used as the foundation of buildings (structures).

[0003] The compaction method is a commonly used method for treating collapsible loess foundations. However, if the water content of the foundation soil is too high, engineering problems such as hole collapse and necking will often occur during the drilling process. The existing treatment methods are relatively rough, mostly directly filling with hygroscopic materials, which lack specificity for the conditions of each soil layer, and also have disadvantages such as serious material waste, uneconomical, and poor operating environment. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a construction method for quantitative moisture absorption of collapsible loess foundation, so as to solve the problems of poor effect of moisture absorption methods in the prior art.

[0005] The technical solution of the present invention to solve the above technical problems is as follows:

[0006] The present invention provides a construction method for quantitative moisture absorption of collapsible loess foundation, comprising the following steps:

[0007] The number, diameter and position of the moisture absorption holes are determined according to the total moisture absorption treatment water volume, and holes are punched to obtain a plurality of the moisture absorption holes; the formula of the desiccant is determined according to the moisture absorption treatment water volume of at least one soil layer, and a drying device is placed at a corresponding depth position in each of the moisture absorption holes, and the drying device contains the desiccant; moisture absorption is completed after standing still;

[0008] Among them, the total moisture absorption treatment water volume is obtained according to the volume of the loess foundation, the actual moisture content of the soil layer at at least one depth position and the optimal moisture content of the soil layer; the moisture absorption treatment water volume of the soil layer is obtained according to the actual moisture content of the soil layer and the optimal moisture content of the soil layer.

[0009] Based on the above technical solution, the present invention can also be improved as follows.

[0010] Furthermore, there are multiple depth positions, and the height differences of the multiple depth positions are equal; multiple drying devices are placed in each moisture absorption hole, and the positions of the drying devices correspond to the depth positions one by one.

[0011] Furthermore, the drying device is a drying bag, and the material of the drying bag is a water-permeable material.

[0012] Furthermore, the drying device is in contact with the inner wall of the moisture absorption hole.

[0013] Furthermore, the desiccant comprises quicklime and dry sand.

[0014] Furthermore, the actual moisture content is obtained through an in-situ test, and the optimal moisture content is obtained through a compaction test.

[0015] Furthermore, before the drilling is performed, a test soil pile is firstly performed to determine the shrinkage position of each moisture absorption hole.

[0016] Furthermore, before placing at least one drying device in each of the moisture absorption holes, a sleeve is first inserted into each of the moisture absorption holes, and then each of the drying devices is placed in the sleeve, and finally the sleeve is removed.

[0017] Furthermore, after placing at least one drying device in each of the moisture absorption holes, the method further includes setting at least one rainproof device within the area of ​​the loess foundation.

[0018] Furthermore, the standing time is 1 to 5 days.

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

[0020] (1) The construction method of quantitative moisture absorption of collapsible loess foundation of the present invention determines the parameters of the moisture absorption holes according to the total moisture absorption water amount, which can effectively improve the moisture absorption efficiency and effect;

[0021] (2) The construction method of quantitative moisture absorption of collapsible loess foundation of the present invention determines the ratio of desiccant according to the moisture absorption of soil layer, which can more evenly control the moisture content of soil layers at different depths, making the moisture content of soil layers at different depths tend to the optimal moisture content more obviously, and achieving better effect of moisture absorption treatment on foundation;

[0022] (3) The construction method of quantitative moisture absorption of collapsible loess foundation of the present invention can better control the dryness of the soil within the scope of foundation treatment;

[0023] (4) The construction method for quantitative moisture absorption of collapsible loess foundation of the present invention has the advantages of low cost, strong feasibility, simple required construction equipment, convenient operation and high efficiency, etc. It can improve work efficiency and has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 The construction method for quantitative moisture absorption of collapsible loess foundation of the present invention is a flow chart of an embodiment;

[0025] Figure 2 The present invention is a construction method for quantitative moisture absorption of collapsible loess foundation, and a schematic diagram of the construction structure of an embodiment.

[0026] In the accompanying drawings, the components represented by the reference numerals are listed as follows:

[0027] 1. Loess foundation; 2. Moisture absorption hole; 3. Drying bag; 4. Diameter reduction position; 5. Casing; 6. Drilling machine. DETAILED DESCRIPTION

[0028] The principles and features of the present invention are described below in conjunction with the accompanying drawings. The examples given are only used to explain the present invention and are not used to limit the scope of the present invention.

[0029] The construction method for quantitative moisture absorption of collapsible loess foundation of the present invention comprises the following steps:

[0030] The number, diameter and position of the moisture absorption holes are determined according to the total moisture absorption treatment water volume, and holes are punched to obtain a plurality of moisture absorption holes; the formula of the desiccant is determined according to the moisture absorption treatment water volume of at least one soil layer, and a drying device containing the desiccant is placed at a corresponding depth position in each moisture absorption hole; moisture absorption is completed after standing still;

[0031] Among them, the total moisture absorption treatment water volume is obtained according to the volume of the loess foundation, the actual moisture content of the soil layer at at least one depth position and the optimal moisture content of the soil layer; the moisture absorption treatment water volume of the soil layer is obtained according to the actual moisture content of the soil layer and the optimal moisture content of the soil layer.

[0032] The construction method of quantitative moisture absorption of collapsible loess foundation of the present invention is to make holes according to the moisture absorption treatment water volume, so that the position setting of the moisture absorption hole can be more scientific and reasonable; the corresponding desiccant is placed according to the moisture absorption treatment water volume of soil layers of different depths, so that the dryness of the soil body can be better controlled within the foundation treatment range, and compared with the traditional treatment method, the water content of soil layers of different depths can be more evenly controlled, so that the water content of soil layers of different depths tends to the optimal water content more obviously, and the effect of moisture absorption treatment of the foundation is better. The method of the present invention is low in cost, strong in feasibility, has the advantages of simple structure, convenient operation, high efficiency, etc., can improve work efficiency, and has a wide range of application prospects.

[0033] In the method of the present invention, the water content refers to the percentage of the mass of water contained in a unit volume of loess to the mass of soil particles, and the moisture absorption treatment water volume refers to the mass of water that theoretically needs to be absorbed by the desiccant. Since the desiccant needs to be fixedly placed at a specific depth position in actual use, it is necessary to determine the specific formula of the desiccant according to the moisture absorption treatment water volume at the depth position, and the moisture absorption treatment water volume at the depth position is calculated by the difference between the actual moisture content of the soil layer at the depth position and the optimal moisture content of the soil layer.

[0034] For a whole loess base plot, since it has a certain depth, the actual water content and the optimal water content of the soil layer at different depths are different, and the plot has a certain area, the depth, pore size, and specific distribution position of the hygroscopic pores need to be determined according to the total hygroscopic water volume of the plot. However, the actual and accurate total hygroscopic water volume of the plot cannot be obtained completely accurately without destroying the plot on a large scale. Therefore, it can be estimated by measuring the actual water content and the optimal water content of the soil layer at at least one depth position, and combining it with the volume of the plot.

[0035] In the method of the present invention, the formula for estimating the volume of the treated foundation and the moisture absorption is:

[0036]

[0037] In formula (1): Q is the calculated water absorption (t);

[0038] υ is the total volume of the pseudo-hygroscopic soil (m 3 );

[0039] is the average dry density of the pseudo-hygroscopic soil (t / m 3 );

[0040] is the average moisture content of the soil before moisture absorption (%);

[0041] ω op is the optimum moisture content of soil (%);

[0042] k is the diffusion coefficient, which can be between 1.05 and 1.1.

[0043] The method for estimating the number and diameter of hygroscopic pores is:

[0044]

[0045] In formula (2): N is the number of moisture absorption pores;

[0046] Q is the calculated water absorption (t);

[0047] D is the diameter of the moisture absorption hole (m), which can be 1 / 3 to 1 / 2 of the diameter of the soil-squeezing pile;

[0048] is the average moisture absorption depth of the moisture absorption pores (m).

[0049] Of course, the more depth positions are measured, the more accurate the estimated result will be. When only one depth position is measured, it is generally the bottom position of the moisture absorption hole.

[0050] Preferably, there are multiple depth positions, and the height differences of the multiple depth positions are equal; multiple drying devices are placed in each moisture absorption hole, and each drying device corresponds to a depth position one by one.

[0051] Preferably, the total area and depth of the loess foundation need to be determined before construction. The scope can be determined according to specific needs, or according to the engineering geological survey report and relevant regulations of the specification.

[0052] Preferably, before measuring the actual soil moisture content and the optimum soil moisture content, it is also necessary to determine the location, number, size and distribution of the soil-squeezing piles according to relevant specifications, and then conduct trial driving of the soil-squeezing piles to preliminarily determine the shrinkage hole locations of the high-humidity loess foundation.

[0053] Preferably, after completing the trial soil squeezing piles, an in-situ test is performed to determine the actual moisture content of the soil layers at different depths within the construction site, and then a compaction test is performed to measure the optimal moisture content of the soil layers at each depth.

[0054] In actual construction, multiple drying devices are usually placed in sequence at the bottom of the moisture absorption hole. It is sufficient as long as the desiccant formula in one drying device corresponds to the moisture absorption amount of the soil layer. However, in order to improve the moisture absorption effect, it is best that the desiccant formula of each drying device corresponds to the moisture absorption amount of the soil layer where it is located.

[0055] More preferably, the drying device is a drying bag, and the drying bag is made of a water-permeable material. Specifically, the shape of the drying bag is adaptive and has no fixed shape. Under the influence of its own weight, the shape can be changed according to external constraints, so that it can fit more fully with the pile hole wall, thereby ensuring the moisture absorption effect.

[0056] In addition, the components of the desiccant include quicklime and dry sand, and the material of the drying bag is preferably a material that is easy to burst after absorbing water. In this way, when the absorbed moisture reaches a certain level, the quicklime in the drying bag reacts with the sand, expands in volume, and the drying bag bursts. In the process of moisture absorption, the mixture in the drying bag also reacts and expands in volume, which produces a certain compaction effect, thereby enhancing the effect of foundation treatment.

[0057] Preferably, the mass ratio of quicklime and dry sand is determined according to the actual moisture content of soil layers at different depths and the optimal moisture content of soil layers, so that the water absorption capacity of the drying bag can be adjusted. After the moisture absorption capacity of the drying bag is determined, the number of drying bags required for moisture absorption of each soil layer is determined according to the moisture absorption amount of each soil layer.

[0058] Preferably, the size of the drying bag is matched with the number and diameter of the moisture absorption holes, and the size of the drying bag should be close to the size of the moisture absorption pile hole, and the diameter is slightly smaller than the moisture absorption pile hole, so as to facilitate the drying bag to smoothly enter the moisture absorption hole.

[0059] Generally, since the diameter of the moisture absorption hole is not large, for a soil layer of a certain depth, only one desiccant bag is needed, and the desiccant in the desiccant bag can meet the moisture absorption demand of the soil layer. However, in some cases, for a soil layer of a certain depth, the corresponding desiccant can be divided into two or more desiccant bags. Regardless of the placement method, it is necessary to ensure that the hole wall of the moisture absorption hole can contact the desiccant.

[0060] In addition, since a soil layer has a certain height, in order to make the moisture absorption effect more accurate, the height of the drying bag (desiccant) corresponding to the soil layer is equal to the height of the soil layer. In this way, each depth of the soil layer can correspond to a drying bag (desiccant) that matches the moisture absorption amount of the soil layer.

[0061] However, in some actual operations, fewer locations are measured. For example, only the moisture absorption of the soil layer at the bottom and middle of the moisture absorption hole is measured, and there are multiple soil layers with unknown (unmeasured) moisture content between these two soil layers. In this case, except for the soil layer at the bottom and middle of the moisture absorption hole, the desiccant formula placed in other soil layers can be the same as the desiccant corresponding to the bottom soil layer or the desiccant formula of the middle soil layer.

[0062] Preferably, under normal circumstances, the volume mixing ratio of dry sand and quicklime can be about 2:3; when the water content is greater than 20%, the volume mixing ratio of dry sand and quicklime can be about 1:2.

[0063] Preferably, the drying bag can be directly put into the moisture absorption hole. However, in order to prevent the drying bag from being stuck on the inner wall of the moisture absorption hole or the shrinkage hole, after the drilling is completed, the moisture absorption holes are firstly re-drilled with a casing to ensure that the drying bag can smoothly pass through the shrinkage hole. Then, the prepared drying bags are put into the casing according to the calculated number. When all the drying bags have been put into the casing according to the design, the casing is pulled out. At this time, the drying bag is in direct contact with the foundation soil, and the quicklime and dry sand in the drying bag are used to absorb and fix the soil moisture within the foundation treatment range.

[0064] Preferably, after placing at least one drying device in each moisture absorption hole, the method further includes setting a rainproof device within the area of ​​the loess foundation to prevent weather conditions from interfering with the moisture absorption effect of the foundation.

[0065] Preferably, the standing time is 1 to 5 days; standing allows the desiccant in the drying bag to fully function, and the quicklime therein fully reacts with the sand, thereby making the soil moisture content close to the optimal soil moisture content, thereby achieving the expected effect of foundation moisture absorption treatment.

[0066] After the moisture absorption construction is completed, there is no need to remove the desiccant, which greatly simplifies the construction steps and effectively improves the efficiency of the moisture absorption construction.

[0067] The present invention is specifically described below by means of specific embodiments:

[0068] Example

[0069] like Figure 1 and 2 As shown, this embodiment adopts the method of the present invention to carry out quantitative moisture absorption construction on the collapsible loess foundation 1, and the specific steps are as follows:

[0070] (1) Determine the scope and depth of the foundation that needs moisture absorption treatment: Based on the engineering geological survey report and relevant regulations, determine the scope and depth of the collapsible loess foundation 1 that needs moisture absorption treatment.

[0071] (2) Determine the location of soil-squeezing piles: According to relevant specifications, determine the foundation treatment plan for soil-squeezing piles, including the required number of piles, pile size and their distribution.

[0072] (3) Trial driving of soil-squeezing piles: According to the arrangement and size of the soil-squeezing piles determined in step (2), trial driving of soil-squeezing piles is performed to preliminarily determine the diameter shrinkage position 4 of the soil-squeezing piles on the collapsible loess foundation 1.

[0073] (4) Measuring the actual soil moisture content and the optimum soil moisture content: Conduct an in-situ test to measure the actual soil moisture content, conduct a compaction test, and measure the optimum soil moisture content. In this embodiment, the actual soil moisture content and the optimum soil moisture content are measured at nine depths equidistantly from the bottom of the moisture absorption hole 2 to the ground.

[0074] (5) Determine the number and position of the moisture absorption holes 2: Calculate the total amount of water required for moisture absorption treatment based on the area and depth of the collapsible loess foundation 1 that needs to be treated, as well as the actual moisture content of each soil layer and the optimal moisture content of each soil layer, and determine the number, pore size, and position of the moisture absorption holes 2, and locate the positions.

[0075] (6) Drilling construction: Drilling is performed using a drilling machine 6.

[0076] (7) Making the drying bag 3: Match the specifications and dimensions of the drying bag 3 according to the number and diameter of the moisture absorption holes 2. The moisture absorption material in the drying bag 3 is composed of a mixture of quicklime and dry sand in different proportions. The bag body material of the drying bag 3 is a material with good water permeability and easy to burst after absorbing water. The size of the drying bag 3 is close to the size of the moisture absorption pile hole, and the diameter is slightly smaller than the diameter of the moisture absorption hole 2, so that the drying bag 3 can smoothly enter the moisture absorption hole 2.

[0077] (8) Estimation of the required number of drying bags 3: The moisture absorption is estimated based on the difference between the moisture content of each soil layer and the maximum moisture content, and the ratio of quicklime to dry sand in the drying bag 3 is adjusted according to the moisture content of each soil layer to control the moisture absorption capacity of the drying bag 3. After the moisture absorption capacity of the drying bag 3 is determined, the number of drying bags 3 required for moisture absorption of each soil layer is determined according to the moisture absorption required by each soil layer.

[0078] In this embodiment, each soil layer at a depth corresponds to a drying bag 3 .

[0079] (9) Placement of drying bag 3: To ensure that the drying bag 3 can smoothly enter the moisture absorption hole 2, the present embodiment uses the sleeve 5 to punch again after the holes are punched, ensuring that the drying bag 3 can smoothly pass through the diameter reduction position, and then puts the prepared drying bag 3 into the sleeve 5. When the drying bag 3 is completely put into the sleeve 5, the sleeve 5 is pulled out. At this time, the drying bag 3 is in direct contact with the foundation soil, and the quicklime and dry sand in the drying bag 3 are used to absorb and fix the soil moisture within the scope of the foundation treatment. When the absorbed moisture reaches a certain level, the quicklime in the drying bag 3 reacts with the sand, expands in volume, and the drying bag 3 bursts. In the process of moisture absorption, the mixture in the drying bag 3 also reacts and expands in volume, which produces a certain compaction effect, thereby enhancing the effect of the foundation treatment.

[0080] (10) Laying waterproof tarpaulin: After the drying bag 3 is placed, a layer of waterproof tarpaulin 7 is laid on each moisture absorption hole 2 to prevent weather conditions from interfering with the moisture absorption effect of the foundation.

[0081] (11) Standing: Standing for 1-2 days to allow the drying bag 3 to fully function and the quicklime in the drying bag 3 to fully react with the sand and soil, thereby making the soil moisture content close to the optimal soil moisture content, thereby achieving the expected effect of foundation moisture absorption treatment.

[0082] In the description of the present invention, it should be noted that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0083] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0084] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0085] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0086] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0087] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A construction method for quantitative moisture absorption of collapsible loess foundation, characterized in that: The following steps are involved: Determine the number, diameter and position of the moisture absorption holes according to the total moisture absorption treatment water volume, and perform drilling to obtain a plurality of the moisture absorption holes; Determine the formula of the desiccant according to the amount of water absorbed by at least one soil layer, and place a drying device containing the desiccant at a corresponding depth position in each of the moisture absorption holes; After standing, moisture absorption is completed; Among them, the total moisture absorption treatment water volume is obtained according to the volume of the loess foundation, the actual moisture content of the soil layer at at least one depth position and the optimal moisture content of the soil layer; the moisture absorption treatment water volume of the soil layer is obtained according to the actual moisture content of the soil layer and the optimal moisture content of the soil layer.

2. The construction method for quantitative moisture absorption of collapsible loess foundation according to claim 1, characterized in that: There are multiple depth positions, and the height differences of the multiple depth positions are equal; multiple drying devices are placed in each moisture absorption hole, and the positions of the drying devices correspond to the depth positions one by one.

3. The construction method for quantitative moisture absorption of collapsible loess foundation according to claim 2, characterized in that: The drying device is a drying bag, and the material of the drying bag is a water-permeable material.

4. The construction method for quantitative moisture absorption of collapsible loess foundation according to claim 3 is characterized in that: The drying bag is in contact with the inner wall of the moisture absorption hole.

5. The construction method for quantitative moisture absorption of collapsible loess foundation according to claim 4, characterized in that: The desiccant comprises quicklime and dry sand.

6. A construction method for quantitative moisture absorption of collapsible loess foundation according to any one of claims 1 to 5, characterized in that: The actual moisture content of the soil layer is obtained through an in-situ test, and the optimal moisture content of the soil layer is obtained through a compaction test.

7. A construction method for quantitative moisture absorption of collapsible loess foundation according to any one of claims 1 to 5, characterized in that: Before the drilling is performed, a test soil pile is firstly performed to determine the shrinkage position of each moisture absorption hole.

8. A construction method for quantitative moisture absorption of collapsible loess foundation according to claim 7, characterized in that: Before placing the drying device at the corresponding depth position in each moisture absorption hole, a sleeve is first inserted into each moisture absorption hole, then each drying device is placed in the sleeve, and finally the sleeve is removed from the moisture absorption hole.

9. A construction method for quantitative moisture absorption of collapsible loess foundation according to any one of claims 1 to 5, characterized in that: After placing the drying device at the corresponding depth position in each of the moisture absorption holes, the step also includes setting at least one rainproof device within the area of ​​the loess foundation, so that at least all of the moisture absorption holes are covered.

10. A construction method for quantitative moisture absorption of collapsible loess foundation according to any one of claims 1 to 5, characterized in that: The standing time is 1 to 5 days.

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