CN101813690B - Testing device for simulating warp self-weight settlement consolidation process by settlement column indoors - Google Patents

Abstract

The invention discloses an indoor settling column simulating test device for sedimentation and consolidation process of alluvial soil, which comprises a settling column of organic glass tubes, a mud agitator, a soil sample fetcher and the like. The column body of the settling column is connected to the base, and a paper ruler is pasted outside the wall of the column body. The slurry suspension is injected into the plexiglass tube behind the settling column, inserted into the stirrer to stir up and down, and evenly mixed. The mouth of the column body is sealed with a film. After sealing, seal it with a rubber band, and record the drop height of the turbid liquid level over time by observing the graduated paper ruler on the outside of the pipe wall, and study the law of free settlement of the silt soil under the action of its own weight; Soil was collected from different layers to measure the void ratio e of soil layers at different depths, to study the self-weight consolidation law of alluvial soil, and to calculate the soil consolidation coefficient c _v . The test device has the characteristics of small footprint, convenient operation, accurate and reliable data observation, less water loss, and small disturbance of soil samples, etc. middle.

Description

Experimental device for indoor sedimentation column simulation of self-gravity deposition and consolidation process of silt soil

technical field

The invention belongs to the interdisciplinary technical field of geotechnical engineering basic test and environmental engineering, and in particular relates to an indoor settlement column simulating test device for the self-gravity deposition and consolidation process of alluvial soil.

Background technique

Settlement column test is an important test device for studying sedimentation and self-weight consolidation of river-lake and marine sedimentary soils. The settling column test device can be used to simulate and measure the self-weight consolidation coefficient c _v of sedimentation mud at different concentrations. The test results provide basic engineering parameters for river dredging and widening projects, port dredging and treatment projects, lake protection and pollution control projects, etc., and provide necessary technical support for project implementation plans and design ideas through indoor settlement column tests. The research on the self-weight settlement and consolidation process of the soil body can also be applied to the land reclamation project of dredger fill soil, and the indoor simulation test is used to study the settlement deformation law of dredger fill soil under the action of gravity. Therefore, the test of sedimentation column simulating the self-weight settlement and consolidation process of silted soil has important guiding significance in projects such as river channel, lake, port improvement, coastal reclamation and land reclamation.

The soil sample consolidation coefficient c _v can be determined by various test methods. The conventional indoor test is to obtain the relationship curve between the soil settlement s and the duration t through multi-stage loading, and calculate the soil sample consolidation coefficient according to the curve. The indoor consolidation test method to determine the consolidation coefficient is the most commonly used method, but its disadvantages are small test specimens, heavy workload, long test time, high cost and large disturbance of soil samples. Since the soil sample cannot accurately reflect the actual conditions of the construction site, the indoor test results are quite different from the actual value of the site soil, which cannot fully reflect the actual consolidation coefficient of the site soil, and cannot take into account the soil under the stress of the soil's own weight. Body consolidation characteristics.

The indoor settlement column test is to study the sedimentation and consolidation law of soil samples under the action of self-weight stress under the condition of high water content and high void ratio. The initial concentration of the soil sample can be prepared as 2500% to 300%, the soil sample is in a flowing state, and the shear strength is 0. The settlement column test simulates the sedimentation and consolidation process of alluvial soil from granular structure, flocculation structure to self-weight action. The state of the subsiding soil is determined according to the relationship between the height of the actual suspension liquid level and time, and the degree of self-weight consolidation and the consolidation coefficient c _v are determined by the thickness of the soil settlement consolidation. This test device studies the settlement and consolidation characteristics of soil under the action of self-weight stress, which lasts for a long time. The measured self-weight stress consolidation coefficient provides basic parameters for the study of dredger fill soil consolidation settlement and silting soil deposition laws, and the results are relatively accurate.

Contents of the invention

technical problem:

The purpose of the present invention is to improve the indoor consolidation test method, design and develop an indoor settlement column that is suitable for the self-weight settlement and consolidation process of silt soil under the action of high water content, high void ratio, and self-weight stress, and the production and operation process is relatively simple and reliable to simulate silt soil Test device for self-gravity deposition consolidation process.

The purpose of the present invention is achieved through the following technical solutions:

An indoor settling column simulation test device for sedimentation and consolidation process of alluvial soil is characterized in that the device comprises three parts: a settling column, a mud agitator, and a small disturbed soil sampling device. Among them, the settling column is connected with the base by the plexiglass tube body, and the outer wall of the column body is symmetrically provided with a graduated paper scale, and the nozzle of the column body is sealed with a sealing film through a rubber band; the mud agitator is fixedly connected to the bottom metal plate by a metal rod through a screw thread; The small-disturbance soil sample fetcher is fixed by a heat-shrinkable tube to connect the thin-walled ring knife string to the metal handle, and the fixing bolt at the top of the handle is connected to the built-in stopper.

The plexiglass tube of the settling column has a height of 800-1200 mm, a wall thickness of 8-12 mm, and an inner diameter of 100-130 mm; the base is made of plexiglass, with a thickness of 10-15 mm and a diameter of 150-180 mm. Secure the connection with organic glue.

The metal rod of the mud mixer has a length of 1000-1400mm and a diameter of 2-3mm, and is fixedly connected to the metal plate through the end thread; the bottom metal plate has a diameter of 90-120mm, and four drainage holes with a diameter of 20-30mm are symmetrically arranged. an internal thread.

The thin-walled ring knife string of the soil extractor is to connect 10 aluminum alloy single ring knives in series on a solid plastic rod, then wrap it with a heated heat-shrinkable tube to cool and shrink it, then tie it tightly, and then pull out the solid plastic rod. The inner diameter is 15-20 mm, and the height is 10-20 mm. The fixing bolt at the top of the handle is rotated to adjust the relative position of the built-in stopper in the handle.

In order to facilitate the observation of the drop position h of the muddy liquid level over time t, two paper rulers with a minimum scale of 1mm are symmetrically installed outside the tube wall of the settlement column, and the actual settlement position of the muddy liquid level is recorded with a camera for filing. The mud mixer consists of a bottom metal plate with a diameter of 90-120mm, which is connected with a metal rod with a length of 1000-1400mm by threads. Four drainage holes with a diameter of 20-30mm are symmetrically arranged on the bottom metal plate. In order to prevent excessive evaporation of moisture in the upper layer, the sealing film of the nozzle of the settlement column is bound and sealed with a rubber band. The soil sample fetcher adopts a lightweight small-disturbance in-situ soil fetcher, which is mainly composed of a thin-walled ring knife string, a heat shrinkable tube, a handle, a built-in stopper, and a fixing bolt. The single ring knife is made of aluminum alloy, the inner diameter of a single ring knife is 15-20m, and the height is 10-20mm. It is fixed by heat shrinkable tube and connected with the handle; the fixed bolt on the top of the handle is rotated to adjust the relative position of the built-in stopper in the handle The soil is taken in layers in the depth direction of the soil layer.

Before the start of the test, pre-configure the test concentration of alluvial soil mud suspension, inject the suspension into the plexiglass settling column tube, insert the mud mixer and stir evenly for 1 to 2 minutes, reciprocating stirring not less than 30 times. Take out the mud agitator, seal the nozzle of the settlement column with the sealing film, and start the self-gravity deposition and consolidation process of the alluvial soil, record the start time t ₀ . Use a camera to record the actual height of the turbid liquid level at different times, and determine the completion time of soil sample consolidation according to the settlement change curve of the turbid liquid surface of the silted soil, and prepare for the sampling of the consolidated soil sample. Sampling was carried out with a small disturbance in-situ soil fetcher, the void ratio e at different depths of the soil layer was measured, and the consolidation coefficient c _v of the test soil sample was determined according to the consolidation coefficient calculation formula.

Innovation point of the present invention:

1. The body of the settling column is made of plexiglass tube, which has high strength and can withstand large water pressure; the tube wall is uniform and transparent, which is convenient for liquid level reading; the connection between the tube wall and the base has high strength, durability, and good sealing. There is no water leakage and seepage; the processing and production process is simple.

2. A paper ruler with a minimum scale of 1mm is symmetrically set on the outside of the settling column tube wall, and the reading is taken as the average value; to avoid the influence of thermal expansion and contraction of plastic and metal materials, and unequal levels of turbid liquid, improve the reading accuracy;

3. The mouth of the settling column is sealed with a sealing film, which can effectively reduce the volatilization of water and prevent the evaporation of the water surface from reducing too much.

4. Sedimentary soil samples are collected in situ by the "direct method" small disturbance soil fetcher to improve data reliability.

Advantages of the present invention: the test device for simulating the self-gravity deposition and consolidation process of silt soil with indoor settlement column measures the coefficient of settlement and consolidation of silt soil with high water content and high void ratio under the action of its own weight, and studies the early strength of silt soil from the flowing state to the self-weight consolidation settlement. The entire settlement process overcomes the inability to measure the consolidation coefficient of soil samples with high moisture content in general indoor compression consolidation tests, small test specimens, heavy workload, high cost, and large disturbance of soil samples, which must be loaded in stages, and the self-weight stress of soil samples is ignored Disadvantages of factor influence. The test device of the present invention studies the settlement and consolidation characteristics of soil under the action of self-weight stress, and the test lasts for a long time. The measured self-weight stress consolidation coefficient provides basic parameters for the study of dredging fill soil consolidation settlement and silting soil deposition law, and the results are relatively accurate. reliable.

Description of drawings

Accompanying drawing 1 is the settling column schematic diagram of indoor settling column simulation alluvial soil self-gravity deposition consolidation process test device;

Accompanying drawing 2 is the schematic diagram of mud agitator;

Accompanying drawing 3 is the top view of the bottom metal plate of mud agitator;

Accompanying drawing 4 is the schematic diagram of in-situ small disturbance soil fetcher.

Labels in the figure: 1 plexiglass tube column body; 2 settlement column base; 3 graduated paper ruler; 4 nozzle sealing film; 5 rubber band; 6 column body and column bottom cemented connection; 7 mud suspension; 8 metal rod; 9 Bottom metal plate; 10 Drain hole; 11 Chassis internal thread; 12 Thin-wall ring knife string; 13 Heat shrinkable tube;

Detailed ways

Combined with the accompanying drawings of the manual, the test device for the indoor settlement column test to simulate the self-gravity deposition and consolidation process of silt soil is further explained:

The indoor settling column simulates the self-gravity deposition and consolidation process of silt soil. The test device is mainly composed of three parts: a settling column (Fig. 1), a mud mixer (Fig. 2), and a small disturbance soil sample collector (Fig. 3). The specific production and operation process of the test device of the present invention are as follows:

(1) Make the settling column (Fig. 1), make the plexiglass tube column body 1 and the reinforced base 2 respectively with plexiglass, and use an organic adhesive to cement the two to form a reliable column body and column bottom cemented connection 6. Among them, the plexiglass tube body 1 has a height of 1000mm, an inner diameter of 130mm, and a wall thickness of 10mm; the reinforced base has a diameter of 180mm and a thickness of 10mm; the outer wall of the plexiglass tube body 1 is symmetrically pasted with a paper ruler with a minimum scale of 1mm and fixed with transparent tape.

(2) To make a mud mixer (Fig. 2), use aluminum alloy materials to make a metal rod 8 with a diameter of 2 mm and a length of 1200 mm and a bottom metal plate 9 with a diameter of 120 mm and a thickness of 3 mm; the metal rod 8 passes through the internal thread 11 of the chassis and the bottom metal plate 9 Reliable connection; four 20mm diameter drainage holes are symmetrically arranged on the bottom metal plate.

(3) Make small disturbance soil sample soil extractor (Fig. 3), adopt stainless steel circular tube to make handle 15 and thin-wall ring cutter string 12, handle inner diameter 18mm, length 1000mm, single ring cutter inner diameter 18mm, wall thickness 0.5mm, height 10mm; 10 A single ring knife is fixed in series with a solid plastic rod, then wrapped with a heated heat-shrinkable tube, tightened after cooling and shrinking, and then the plastic rod is pulled out, fixed by the heat-shrinkable tube 13 to form a thin-walled ring knife string 12, and connected with the handle 15 The heat-shrinkable tube 13 is heat-shrunk and tightened; the built-in stopper 14 is placed in the handle. The thin metal rod of the stopper is 1000mm long, and the bottom metal plate has a diameter of 17mm. There are four symmetrical air holes with a diameter of 2mm on the plate. The thin metal rod It is threadedly connected with the bottom metal plate, and the relative position of the built-in stopper 14 is adjusted by the up and down rotation of the fixing bolt 16 at the upper end of the handle.

(4) Mixer breaks up the undisturbed soil and configures the concentrated silt soil for the initial settlement mud suspension 7 for the test, transfer the mud suspension 7 to the plexiglass tube settlement column 1, and see if there is water seepage at the 6 cemented joints between the column body and the column bottom.

(5) Insert the mud agitator (Fig. 2) into the mud suspension 7, and reciprocate up and down for 1 to 2 minutes, and the number of agitations is not less than 30 times. After the agitation is completed, take out the agitator and add water to the predetermined height of 950mm.

(6) The nozzle of the column body is covered with the sealing film 4, and tightly sealed with a rubber band 5. The mud suspension 7 starts to settle freely under its own weight. According to the reading records of the scale paper ruler 3 on the outer wall of the organic glass column body 1, use The camera takes photos and records the actual settlement height of the turbid liquid surface for archiving.

(5) After the settlement and consolidation of the mud suspension 7 is completed, take samples in situ with a small disturbance soil sampler (Figure 3), and take samples with 12 thin-walled ring knife strings to measure the void ratio of the consolidated soil samples at different depths, and the soil sample consolidation coefficient c _v calculation formula to determine the actual consolidation coefficient of alluvial soil.

Claims (4)

1. an indoor settling leg simulation warp deposits the consolidation process test unit; It is characterized in that this device comprises settling leg; Slurry agitator, microvariations soil sample soil sample barrel three parts are formed; Wherein settling leg is connected with base (2) by plexi-glass tubular shaft (1), and the shaft outer wall is symmetrical set scale paper chi (3), and the shaft mouth of pipe seals through bungee (5) colligation with diaphragm seal (4); Slurry agitator is fixedly connected with substrate dish (9) through screw thread by Metallic rod (8); Microvariations soil sample soil sample barrel by heat-shrink tube (13) fixedly thin-walled cutting ring string (12) be connected with metal handle (15), the set bolt on handle top (16) is connected with built-in retaining plug (14).

2. indoor settling leg simulation warp according to claim 1 deposits the consolidation process test unit, it is characterized in that the high 800～1200mm of plexi-glass tubular shaft (1) of described settling leg, wall thickness 8～12mm, internal diameter 100～130mm; Described base (2) is made for organic glass, thickness 10～15mm, diameter 150～180mm, and plexi-glass tubular shaft (1) is fixedly connected with organic gel with base (2).

3. according to right 1 described indoor settling leg simulation warp deposition consolidation process test unit, it is characterized in that Metallic rod (8) length 1000～1400mm of described slurry agitator, diameter 2～3mm is fixedly connected with substrate dish (9) through end thread; Substrate dish (9) diameter 90～120mm is symmetrical set four diameter 20～30mm draining circular holes (10), and there is an internal thread (11) in central authorities.

4. indoor settling leg simulation warp deposition consolidation process test unit according to claim 1; The thin-walled cutting ring string (12) that it is characterized in that said soil sample barrel is that the monocycle cutter with 10 aluminium alloys is connected on the solid plastic rod; Tighten after shrinking with the heat-shrink tube outsourcing cooling of heating then; Extract solid plastic rod again; Single cutting ring internal diameter 15～20mm, high 10～20mm, the relative position of set bolt (16) the built-in retaining plug of rotation adjusting (14) in handle (15) on described handle (15) top.

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