CN102636631A - Test device and method for judging soil layer collapsibility - Google Patents
Test device and method for judging soil layer collapsibility Download PDFInfo
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- CN102636631A CN102636631A CN2012101165394A CN201210116539A CN102636631A CN 102636631 A CN102636631 A CN 102636631A CN 2012101165394 A CN2012101165394 A CN 2012101165394A CN 201210116539 A CN201210116539 A CN 201210116539A CN 102636631 A CN102636631 A CN 102636631A
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Abstract
The invention provides a test device and method for judging soil layer collapsibility. The test device comprises an outer sleeve, a push rod and a data processor, which are sequentially connected from a conical probe; a soil moisture detector and a stress sensor are arranged in the conical probe; the soil moisture detector comprises a load resistor and a moisture sensor and is used for detecting the water content in the soil body; the stress sensor comprises a strain gauge and a support column and is used for measuring the penetration resistance of the conical probe; and a water injection device is also arranged in the test device and used for simulating the critical water content in the strength test of a soil body. The test device provided by the invention is small in volume, is easy to operate and can be applied to the primary judgment of the loess collapsibility; the test device can primarily determine the interface between the collapsibility soil layer and the non-collapsibility soil layer and the thickness of the collapsibility soil layer without excavating or sampling the field oil layer, so as to determine the lower-limit depth of the collapsibility soil layer and further determine the sampling depth of the exploratory well in reconnaissance; and the test device has obvious superiority in large-area soil property investigation.
Description
Technical field
The present invention relates to the Geotechnical Engineering field tests, relate in particular to proving installation and method of testing thereof that a kind of soil layer settlement by soaking is judged.
Background technology
In the construction project design of Collapsible Loess District; The boundary of the saturated yielding type of foundation soil, saturated yielding grade and the plane and the degree of depth; Be directly connected to the basic type selecting and the method for processing foundation of buildings, also just be related to duration, cost and the quality assurance of foundation certainly.National standard " Code for building construction in collapsible loess zone " is reconnoitred in the joint requiring " should have the controlled exploratory spot that fetches earth of some to penetrate yellow soil horizon of collapsibility " in the regulation of the exploratory spot degree of depth at the scene.In practical operation, the collapsible soil layer thickness in some place can be with reference to the existing Geotechnical Engineering data estimation in contiguous place, to confirm the prospect pit sampling depth; The collapsible soil layer thickness can't be foreseen in some place; Have only through carrying out laboratory soil test after the prospect pit sampling and obtain; This just causes the prospect pit sampling time can't confirm sampling depth, and prospect pit has been made the exploratory spot that fetches earth fail to penetrate the problem of yellow soil horizon of collapsibility after the shop experiment by backfill.So be necessary before the prospect pit sampling, to adopt a kind of simple and efficient way that soil layer is carried out the judgement of settlement by soaking, to confirm the prospect pit sampling depth.
Summary of the invention
The technical matters that the present invention will solve be for provide a kind of volume little, simple to operate, can be used for in-situ testing device that collapsibility of loess is judged, and parameters such as stratum compressibility and bearing capacity can be provided.
The present invention provides a kind of proving installation that the soil layer settlement by soaking is judged that is used for; This proving installation comprises outer sleeve, pushing ram and the data processor that begins to connect successively from conical probe; Include soil moisture detector and strain gauge in the described conical probe; The soil moisture detector comprises moisture transducer and pull-up resistor, and strain gauge comprises resistance strain gage and fore-set, comprises message input device and information output apparatus in the described data processor; Data processor adopts lead to pass pushing ram and is connected in the probe; And through deconcentrator the cable inside conductor is told to be connected to and be used to gather electronic signal in the conical probe, also having water filling device in the described proving installation, this water filling device comprises water filling switch, water transport channel and water filling ring; Said water filling ring comprises dividing plate with holes, gravel and apopore, is positioned at the cylinder outer wall distribution apopore of conical probe and outer sleeve junction; Above-mentioned water transport channel is divided two parts, and a part is annular water transport channel, and another part is a water-supply-pipe; Wherein annular water transport channel is positioned at outer sleeve and near the barrel of outer sleeve; Annular water transport channel and outer sleeve common axis, water-supply-pipe is positioned at pushing ram and is connected with annular water transport channel, and there is the sealing gasket snare this junction; The water filling switch is arranged on the water inlet of water-supply-pipe; After opening the water filling switch, current get into annular water transport channel through water-supply-pipe, and the apopore through the water filling ring gets in the soil again.
Above-mentioned outer sleeve can be cylinder type metal-coating tube; The double-deck centre that water transport channel and water filling ring are made up of outer wall and inwall has the around shaping drum of cavity to constitute; Upper inside wall is porose joins with water-supply-pipe, and the bottom is separated out the high part filling of 10～20mm gravel as the water filling ring with dividing plate.Water filling ring and water transport channel are same around shaping drum, so its making is simple, and being separated out the water filling ring is that the porose height of outer wall can not be too high because only need at the porose position filling gravel of outer wall, and ability water outlet smoothly gets final product.The purpose that water transport channel is made the circular passage is that water can be evenly distributed in the water filling ring and injects soil.The water filling switch is arranged on the water inlet of water-supply-pipe, open the water filling switch after, current get into annular water transport channel through water-supply-pipe, get in the soil through the water filling ring again.
Volume of the present invention is little, simple to operate, can directly make an experiment to the original position soil body at the scene, measures saturated yielding soil thickness and interphase; Has the simple and direct advantage; Said proving installation soil layer does not at the scene excavate under the sampling situation, through in-situ test the settlement by soaking of the soil body is judged, tentatively confirms the interphase and the saturated yielding soil thickness of settlement by soaking and non-settlement by soaking soil layer; Confirm the settlement by soaking soil layer lower limit degree of depth with this, and then the sampling depth of prospect pit when confirming prospecting; For large-area soil nature investigation, superiority is especially obvious, need not excavate, and is time saving and energy saving.
Said annular water transport channel is called cylinder double wall passage for the ring-like cylinder of cavity is arranged in the middle of double-deck, and its cylinder double walled gap is 3～6mm, and wherein cylinder double walled gap is preferably 5mm, can reach best flood effectiveness; Said water filling ring is positioned at the junction of conical probe and outer sleeve; The top is separated by dividing plate with holes and water transport channel, and dividing plate with holes is used to separate outer sleeve and gravel, is filled with the gravel particle of diameter 1.5～2.5mm in the water filling annular space chamber; The diameter of this gravel particle is preferably 2mm; Mainly be the filtering layer effect, can either have prevented that earth from stopping up waterflood path, can let the water that injects pass through smoothly again; Water filling ring cylinder outer wall a large amount of apertures that distribute are the apopore of 0.8～2mm, and the aperture of apopore is preferably 1mm, and under this aperture, draining smoothly can stop simultaneously the gravel in the cavity to spill again.
Above-mentioned water filling ring cylinder outer wall distributed aperture is the apopore of 0.8～2mm, can adopt the apopore in different apertures according to different soil, and for common loess formation, the aperture is that the 1mm effect is best, and draining smoothly can prevent that again apopore is blocked.
Further improvement of the present invention is that the height of water filling ring is 1～3cm, and the top plan of promptly filling gravel and apopore is 1～3cm apart from the height of conical probe awl baseplane; The cone point angle of conical probe is generally 55～65 degree, and wherein 60 degree are preferred point angles, and under this angle, the resistance that conical probe advances is moderate, can obtain good test data; The cone bottom surface diameter of conical probe is 3～5cm, and wherein preferred diameter is 4.5cm, at this moment the about 16cm of area on projecting plane
2, i.e. cone bottom area; The awl point of the cone of conical probe is a ball-type; Ball-type awl point is the sharp plane of awl with the tangent circular cross section of cone; This diameter of boring sharp plane is 1.5～3mm, and wherein preferred diameter is 2mm, after the awl point is cut into ball-type; The resistance that in soil, advances becomes evenly, more helps improving the degree of accuracy of test data.
This invention instrument can directly make an experiment to the original position soil body at the scene, measures saturated yielding soil thickness and interphase, has the simple and direct advantage.It is based on following theoretical realize: in the non-settlement by soaking soil layer, the intensity of unsaturated soil is higher than saturated soil, slowly descends with its intensity of increase of water cut; In the settlement by soaking soil layer; Earth structure strength shows as higher intensity when lower initial water content; But along with the increase of water cut, soil structures is destroyed by immersion, and its intensity reduces rapidly thereupon; When water cut is brought up to certain value when (or being called critical moisture content), just no longer there has been structural strength.Thereby whether through comparing the Strength Changes of the natural moisture content soil body and the saturated soil body, can just declare loess is collapsible loess; The intensity of the soil body is then measured through the conical probe penetration resistance.
The present invention also provide a kind of judge according to above-mentioned proving installation the method for testing of soil layer settlement by soaking comprise following test judgement step:
1) the proving installation top is applied a power, conical probe at the uniform velocity is pressed in the soil, record the penetration resistance of a certain degree of depth place soil, calculate the intensity of this place's soil, wherein, relation: τ=aR-b below said penetration resistance and soil shear strength directly exist;
Wherein, undrained shear strength τ is with soil body ultimate bearing capacity q
uExist and concern τ=q as follows
u/ c, said c are coefficient, 2＜c＜3, and the cone floorage relation of said native state soil strength and conical probe is: P=q
uS;
2) open water valve, add water and make conical probe position soil layer survey the saturated soil strength at this place to saturated back;
3) through the variation of intensity before and after the soil body immersion relatively, judge the settlement by soaking of soil layer, wherein, during P>=6MPa, be judged to be non-collapsible soil; During P＜6MPa, work as p/p
m, be judged to be collapsible soil at>=3.5 o'clock; During P＜6MPa, work as p/p
m, be judged to be non-collapsible soil at＜3.5 o'clock;
Wherein, said p is the native state soil strength, p
mBe the state of saturation soil strength.
More detailed, the method for testing of said judgement soil layer settlement by soaking is explained as follows: at first, the proving installation top is applied a power; Conical probe at the uniform velocity is pressed in the soil, records the penetration resistance of a certain degree of depth place soil, can calculate the intensity of this place's soil; Wherein, The afterburning method of this conical probe is: counterforce device is set on the ground, through oil pressure unit, the proving installation top is applied penetrating power.
Then, when needing to differentiate soil body settlement by soaking, open the water filling switch, add water to conical probe position soil layer is surveyed this place to saturated back saturated soil strength.
The soil body that the sharp volume on every side of awl is V is from natural moisture content ω
0Add water to saturation moisture content ω
1The time, required water injection rate V
1With awl sharp bottom surface radius r and natural moisture content ω
0Relation below existing:
Through calculating, the natural earth body water content is 400ml～600ml at 8%～12% o'clock required water injection rate, preferably is controlled at 500ml.
And the relation of collapsible loess and non-collapsible loess intensity and water cut is as shown in Figure 3, meets the water saturated yielding when the soil body, and the penetration resistance of the two can produce obvious difference, through the relatively variation of soil body immersion front and back intensity, can just declare the settlement by soaking of loess.
Relation: τ=aR-b below penetration resistance and soil shear strength exist.
In the formula: τ representes soil body undrained shear strength; R representes instrument injection reading; A, b represent the regional experience coefficient respectively; Undrained shear strength τ is with q between the limit bearing capacity
uExist and concern τ=q as follows
u/ c, c are coefficient, and the span of c is 2＜c＜3, desirable c=2.
Thereby P=q
uS, in the formula: P representes soil strength; S representes the cone floorage of conical probe.
At last, collapsibility of loess can be just declared in the variation of and state of saturation intensity natural through the soil body.
Try to achieve soil strength by penetration resistance, can just declare collapsibility of loess according to following relation: if P>=during 6MPa, be judged to be non-collapsible soil; If P＜during 6MPa, work as p/p
m, be judged to be collapsible soil at>=3.5 o'clock; If P＜during 6MPa, work as p/p
m, be judged to be non-collapsible soil at＜3.5 o'clock.
When carrying out above-mentioned test; Soil layer is met the volume change of bringing after the water saturated yielding can produce the space between the conical probe and the soil body; The penetration resistance that this moment, conical probe detected can reduce greatly, and there is following monotonic functional relationship: v=f (qu) in injection speed with static point resistance; Work as q
U1＞q
U2The time, v is arranged
1＜v
2Thereby after the soil body was met the water saturated yielding, penetration resistance can reduce, and according to the relation of monotonic quantity, injection speed can increase.
According to q
uSame v
1Between monotonic relationshi, under the certain situation of injection pressure, q
uReduce with injection speed v increase, after loess was met the water saturated yielding, injection speed increased, and static point resistance can reduce.Thereby increase when very fast when injection speed, explain that penetration resistance has reduced rapidly, can judge that the saturated yielding degree of the soil body is higher this moment.
Collapsible loess is divided into self-weight collapse loess and non-self-weight collapse loess.Self-weight collapse loess is meant the loess of meeting generation saturated yielding under saturated gravity pressure behind the water; When add water to saturated after; Saturated yielding can take place rapidly under the effect of self gravitation; So, under the situation that does not add injection pressure, also can produce the variation of penetration resistance behind the chance water if soil layer is a self-weight collapse loess; Non-self-weight collapse loess is meant that saturated yielding does not take place in loess immersion back under saturated gravity pressure; The loess of saturated yielding only just takes place behind additional certain pressure, when add water to saturated after, significant change can not take place in penetration resistance; When continue to apply to instrument probe into pressure after; Non-self-weight collapse loess can be because saturated yielding take place rapidly in the cause of additonal pressure, when the native land layer is non-self-weight collapse loess, under the situation that applies injection pressure, just has the variation of penetration resistance.
Therefore, the injection speed when the injection speed of conical probe is not soaked increases, and judges that then loess produces saturated yielding; If not adding the variation that injection pressure also can produce penetration resistance, then be judged to be self-weight collapse loess behind the soil layer chance water; If soil layer applying the variation that injection pressure just has penetration resistance, then is judged to be non-self-weight collapse loess.
Conical probe can produce penetration resistance when in the process of probeing into, contacting with the soil body, the probe sensor variable signal that has a resistance, and the signal of this variation will be sent on the measurement instrument on ground.
In the prior art, the judgement of soil body settlement by soaking all is to carry out through the shop experiment of soil sample, and this makes the definite of soil sampling position be inverted in time with the soil sample result; For the large area region sex investigation of soil body settlement by soaking, also existing wastes time and energy and situation about possibly do over again.
Compared with prior art, the present invention has obtained following technique effect: can directly make an experiment to the original position soil body at the scene, measure saturated yielding soil thickness and interphase, have the simple and direct advantage.This device soil layer does not at the scene excavate under the sampling situation; Through in-situ test the settlement by soaking of the soil body is judged; Preliminary interphase and the saturated yielding soil thickness of confirming settlement by soaking and non-settlement by soaking soil layer confirmed the settlement by soaking soil layer lower limit degree of depth with this, and then the sampling depth of prospect pit when confirming to reconnoitre; For large-area soil nature investigation, superiority is especially obvious, and it is time saving and energy saving to excavate.In addition, can also divide, and calculate soil strength and compressibility the soil layer of the original position soil body; Whether reaching regulation for artificial foundation's the processing degree of depth requires also can make intuitively and judges.The proving installation that is used for the judgement of soil layer settlement by soaking of the present invention has the important use meaning aspect the experimental test in collapsible loess place.
Further improvement of the present invention is, the said conical probe of control probe into the degree of depth time, a hour step is controlled to be 50cm, wherein, the step is the spacing distance of two measuring points of conical probe when said.
Wherein, The step be the spacing distance of two measuring points of conical probe when said, the time come from the step-length of each step computing in the interative computation process step, what go on foot when according to the invention is the spacing distance of two measuring points; Be that each measuring point survey undisturbed soil intensity need be pushed ahead 10cm; Immersion is pushed ahead 10cm, again to record the soil strength under the state of saturation then; Consider the coverage of immersion, accomplishing a measuring point needs 30～40cm at least, so in order to guarantee to survey the correctness of test data, it is proper that the distance of two measuring points is got 50cm; Probeing on the degree of depth at every turn and can accurately control, be controlled at when certain within the step, Shi Butai is big, to the resolution rate variance of soil layer; Shi Butai is little, may receive the influence of a measuring point water filling, step effect optimum when the present invention gets 50cm control; Because valve switch to water delivering orifice also has segment distance; So after opening the water filling switch, can wait 2 minutes to 3 minutes, treat that moisture fully infiltrates behind the soil body just reading.
Because the unevenness of soil layer, when cavity, layer of sand or other water-permeable sub-stances appearred in the sharp local soil layer of awl, institute's water filling meeting was run off, and soil layer is reached capacity, if do not control the water yield, the immersion soil layer is corresponding bigger, can influence the measurement of next measuring point.Event need to adopt two control indexs to address this problem, and the one, to the measurement of water cut, reach capacity 70% o'clock of water cut of soil layer stops water filling; The 2nd, the control water yield, water injection rate is not more than 500ml; If just in time there are cavity or layer of sand in the conical probe below; The water of 500ml can be not influential to next test point; Though and water filling but the water cut increase explains that not quite also soil layer is unusual, can give up the next point of this some test, the character of this point can be according to character synthetic determination up and down.
Description of drawings
Fig. 1 is the proving installation synoptic diagram that soil layer settlement by soaking of the present invention is judged;
Fig. 2 is a conical probe water discharging part synoptic diagram of the present invention;
Fig. 3 is the synoptic diagram that concerns of collapsible loess and non-collapsible loess intensity and water cut.
Mark among the figure: 1-moisture transducer; The 2-pull-up resistor; The 3-resistance strain gage; The 4-fore-set; The 5-deconcentrator; The 6-cable; The 7-water transport channel; The 8-data processor; 9-water filling switch; The 10-pushing ram; 11-sealing gasket snare; The 12-outer sleeve; 13-dividing plate with holes; 14-gravel; The 15-apopore; The 16-conical probe; 17-bores point.
Embodiment
Below in conjunction with accompanying drawing, more excellent embodiment of the present invention is done further detailed description:
Proving installation of the present invention is based on following theoretical realize: in the non-settlement by soaking soil layer, the intensity of unsaturated soil is higher than saturated soil, slowly descends with its intensity of increase of water cut; In the settlement by soaking soil layer; Earth structure strength shows as higher intensity when lower initial water content; But along with the increase of water cut, soil structures is destroyed by immersion, and its intensity reduces rapidly thereupon; When water cut is brought up to certain value when (or being called critical moisture content), just no longer there has been structural strength.Thereby whether through comparing the Strength Changes of the natural moisture content soil body and the saturated soil body, can just declare loess is collapsible loess; The intensity of the soil body is then measured through the conical probe penetration resistance.
Embodiment 1:
Proving installation as depicted in figs. 1 and 2, that this example provides a kind of soil layer settlement by soaking to judge comprises the outer sleeve 12, pushing ram 10 and the data processor 8 that connect successively from conical probe 16 beginnings; Outer sleeve 12 is the hollow cylindrical metal body; By thickness is that stainless steel after heat treatment (40Cr) material of 5mm is processed, and its diameter can be 3～5cm, preferred diameter 4.5cm; Highly be 7～10cm, preferred heights is 9cm; The hollow circular-tube that pushing ram 10 is processed for stainless steel (40Cr) material after heat treatment, the pipe external diameter is 1.5cm, and internal diameter is 1cm, and pushing ram 10 can connect continuous continued access from beginning to end and be used for conical probe 16 is continued to be pressed into soil layer; Conical probe 16 is the filled circles cone, is processed by stainless steel (40Cr) material after heat treatment, and there are electronic unit soil moisture detector and strain gauge in inside; The soil moisture detector comprises moisture transducer 1 and pull-up resistor 2, and strain gauge comprises resistance strain gage 3 and fore-set 4, and the fore-set here is a short cylinder; By the solid that 60Si2Mn steel is after heat treatment processed, cross-sectional diameter is 1.5cm, highly is 3.0cm; Be placed in bottom, cylindrical spy tube axis; Be connected with conical probe 16, its effect is under the change in resistance of different awl points 17, to produce different strains, thereby measures the resistance of awl point 17 by the resistance strain gage strain.
Comprising message input device and information output apparatus in the above-mentioned data processor 8, can be a computer or data processing terminal, and the cable 6 in the data processor 8 passes pushing ram 10, is connected to each electronic unit in the conical probe 16; Through deconcentrator 5 cable 6 inside conductors are told on each electronic unit of receiving in the conical probe 16, be used to gather electronic signal.Strain gauge is a penetration resistance in order to the resistance of the entering soil layer of detection conical probe 16; After sensor detected penetration resistance, the variable signal that will have a resistance reached ground data processor 8 through plain conductor shown in Fig. 1, therefore, can be calculated parameters such as soil strength and compressibility by the penetration resistance that detects.
Also has water filling device in the above-mentioned proving installation; This water filling device comprises water filling switch 9, water transport channel 7 and water filling ring; This annular water transport channel is for there being the ring-like cylinder of cavity in the middle of double-deck; The double walled gap of outer sleeve 12 is generally 3～6mm, and preferred gap is 5mm, can reach best flood effectiveness.The circular passage upper inside wall is porose to be connected with water-supply-pipe, and there is sealing gasket snare 11 this junction, and the bottom is separated out the high part of 15mm as the water filling ring with dividing plate; This water filling ring is positioned at the junction of conical probe 16 and outer sleeve 12, is filled with the granular gravel 14 of diameter 1.5～2.5mm in it, and water filling ring top is a dividing plate 13 with holes, and dividing plate 13 with holes is used to separate outer sleeve 12 and gravel 14; The preferred diameter of this gravel 14 is 2mm, mainly has been the filtering layer effect, prevents that earth from stopping up waterflood path, and can let the water that injects pass through smoothly; Water filling ring outer wall a large amount of apertures that distribute are the apopore 15 of 0.8～2mm, and the desirable aperture of apopore 15 is 1mm, and under this aperture, draining can stop the gravel 14 in the cavity to spill again smoothly.
Above-mentioned water filling ring cylinder outer wall distributed aperture is the apopore 15 of 0.8～2mm, can adopt the apopore 15 in different apertures according to different soil, and for common loess formation, the aperture is that the 1mm effect is best, and draining smoothly can prevent that again apopore is blocked.
The water transport channel of said apparatus is divided two parts, and a part is annular water transport channel, and another part is a water-supply-pipe; Wherein annular water transport channel is positioned at outer sleeve and near the barrel of outer sleeve, annular water transport channel and outer sleeve common axis, and water-supply-pipe is positioned at pushing ram 10 and is connected with annular water transport channel; Water filling switch 9 is arranged on the water inlet of water-supply-pipe; After opening water filling switch 9, current get into annular water transport channel through water-supply-pipe, get in the soil through the water filling ring again.
The cone longitudinal section angle of above-mentioned conical probe 16 is generally 55～65 degree; The cone point angle that is conical probe 16 can be 55～65 degree, and wherein 60 degree are preferred angles, under this angle; The resistance that conical probe 16 advances is moderate, can obtain good test data.
The cone bottom surface diameter of above-mentioned conical probe 16 is 3～4cm, and wherein more satisfactory diameter is 4.5cm, the about 16cm of conical base area this moment
2
Further improvement to technique scheme is; The awl point 17 of the cone of described conical probe 16 is a ball-type; The awl point 17 that it is characterized in that the cone of described conical probe 16 is ball-type; Ball-type awl point 17 is 1.5～3mm with the tangent circular cross section diameter of cone, and more satisfactory diameter is 2mm.After awl point 17 was cut into ball-type, the resistance that in soil, advances became evenly, more helped improving the degree of accuracy of test data.
Embodiment 2:
This example provides a kind of method of testing of judging the soil layer settlement by soaking; When this example is used the described proving installation of embodiment 1, can record the resistance of a certain degree of depth place original state loess awl point 17 earlier, and extrapolate the intensity of loess under the natural moisture content; Be filled to saturated for then awl point 17 soil body on every side; Measure the resistance of soil body awl point 17 at this moment again, whether through the relatively variation of the saturated front and back of soil body intensity, just declaring soil layer is collapsible loess.
Practical implementation process of the present invention is; Pushing ram 10 to the proving installation afterbody applies a power; At the uniform velocity be pressed into conical probe 16 in the soil; Conical probe 16 can produce penetration resistance when in the process of probeing into, contacting with the soil body, the probe sensor variable signal that has a resistance, and the signal of this variation will be sent on the data processor 8 on ground.Under the different soil situation, each is variant for penetration resistance, thereby can divide soil layer through penetration resistance.
When needing to differentiate soil body settlement by soaking, open water valve water filling switch 9, add water to conical probe 16 position soil layers to saturated; If the soil body is met the water saturated yielding, penetration resistance can produce significant change, through the variation of penetration resistance; According to the regional experience formula; Soil strength can be calculated,, collapsibility of loess can be just declared through the variation of soil strength.
Embodiment 3:
This example is in 40.00m prospecting depth range, and master stratum is made up of silt shape loess, and is specific as follows:
When 1, using, adopt certain injection pressure, conical probe 16 at the uniform velocity is pressed in the soil, conical probe 16 is pressed into rate controlled between 0.015～0.025m/s.Conical probe 16 can produce penetration resistance when in the process of probeing into, contacting with the soil body, the probe sensor variable signal that has a resistance, and the signal of this variation will be sent on the measurement instrument on ground.
2, resistance strain gage 2 in the conical probe 16 and sensor 3 can be transferred to data acquisition unit through cable 5 with the resistance signal that changes and carry out automatic record, probe into the degree of depth at every turn and are taken as 20cm, and then obtain boring the resistance of point 17 and the relation of the degree of depth.
3, record the resistance of a certain degree of depth place awl point 17 after, open water filling switch 9, water gets into soil layers through the apopore 15 that drainage channel sees through the water filling ring, the electromagnetic wave that moisture transducer produces can be transmitted in the soil, and reflexes to receiver.According to the difference that soil water divides, receiver receives different moisture information, calculates moisture through moisture information again.When native saturation degree greater than 70% or water injection rate when reaching 500ml, close water filling switch 9, stop to add water.Conical probe 16 is probeed into the degree of depth of 20cm, measure the resistance of soil body awl point 17 when saturated.
4, the data that test obtained are according to probeing into degree of depth record item by item, during by the settlement by soaking of the following standard determination soil body: P>=6MPa, are judged to be non-collapsible soil; During P＜6MPa, work as p/p
m, be judged to be collapsible soil at>=3.5 o'clock; During P＜6MPa, work as p/p
m, be judged to be non-collapsible soil at＜3.5 o'clock.
5, if desired, can be according to the variation of penetration resistance with the degree of depth, confirm the parameter such as bearing capacity, modulus in compression of each layer soil through the size of penetration resistance.
6, as shown in the table according to test result to the preliminary judgement of part soil layer settlement by soaking:
Relevant speciality term explanation of the present invention:
Dividing plate with holes 13, gravel 14 and apopore 15 are formed the water filling rings; Moisture transducer 1 is formed the soil moisture detector with pull-up resistor 2; The position of fore-set, shape and action value are: fore-set is a short cylinder; Be placed in bottom, cylindrical spy tube axis; Be connected with taper shape probe 16, be used under the change in resistance of different awl points 17, producing different strains, thereby measure the resistance of awl point 17 by the strain of resistance strain gage.
Wherein, Ks is the sensitivity coefficient of material, and its physical significance is the resistance change rate of unit strain, whether significantly to indicate such material resistance strain gage effect.ε is the strain of measuring point place, is nondimensional amount, but the still unit's of giving microstrain traditionally, conventional sign μ ε representes.
Hence one can see that, and tinsel is when producing strain effect, and strain stress and resistance change rate dR/R are linear, and Here it is utilizes metal strain plate to measure the theoretical foundation of member strain.
Above content is to combine concrete preferred implementation to the further explain that the present invention did, and can not assert that practical implementation of the present invention is confined to these explanations.For the those of ordinary skill of technical field under the present invention, under the prerequisite that does not break away from the present invention's design, can also make some simple deduction or replace, all should be regarded as belonging to protection scope of the present invention.
Claims (9)
1. one kind is used for the proving installation that the soil layer settlement by soaking is judged; Comprise the outer sleeve (12), pushing ram (10) and the data processor (8) that connect successively from conical probe (16) beginning; Said conical probe includes soil moisture detector and strain gauge in (16); The soil moisture detector comprises moisture transducer (1) and pull-up resistor (2); Strain gauge comprises resistance strain gage (3) and fore-set (4), and described data processor comprises message input device and information output apparatus in (8), and data processor (8) adopts cable (6) to pass pushing ram (10) and is connected to conical probe (16); And through deconcentrator (5) cable (6) inside conductor is told and to be connected to conical probe (16) and to be used to gather electronic signal; It is characterized in that also having water filling device in the described proving installation, this water filling device comprises water filling switch (9), water transport channel (7) and water filling ring; Said water filling ring comprises dividing plate with holes (13), gravel (14) and apopore (15), is positioned at the cylinder outer wall distribution apopore (15) of conical probe (16) and outer sleeve (12) junction; Said water transport channel (7) is divided two parts, and a part is annular water transport channel, and another part is a water-supply-pipe; Wherein annular water transport channel is positioned at outer sleeve (12) and near the barrel of outer sleeve (12); Annular water transport channel and outer sleeve (12) common axis, water-supply-pipe is positioned at pushing ram (10) and is connected with annular water transport channel, and there is sealing gasket snare (11) this junction; Water filling switch (9) is arranged on the water inlet of water-supply-pipe; After opening water filling switch (9), current get into annular water transport channel through water-supply-pipe, and the apopore (15) through the water filling ring gets in the soil again.
2. the proving installation that is used for the judgement of soil layer settlement by soaking as claimed in claim 1 is characterized in that:
Said annular water transport channel is a cylinder double wall passage, and its cylinder double walled gap is 3～6mm;
Fill gravel (14) particle of diameter 1.5～2.5mm in the water filling ring of cylinder bottom;
Be distributed with the apopore that the aperture is 0.8～2mm (15) above the water filling ring cylinder outer wall of filling gravel (14).
According to claim 1 or claim 2 be used for the proving installation that the soil layer settlement by soaking is judged, it is characterized in that:
The height of water filling ring is 1～3cm, and the top plan of promptly filling gravel (14) and apopore (15) is 1～3cm apart from the height of conical probe (16) awl baseplane;
The cone point angle of conical probe (16) is 55～65 degree;
The awl point (17) of cone is a ball-type, and the awl point (17) and the tangent circular cross section diameter of cone of ball-type are 1.5～3mm;
The cone bottom surface diameter of conical probe (16) is 3～5cm.
4. the proving installation that is used for the judgement of soil layer settlement by soaking as claimed in claim 3 is characterized in that:
Said annular water transport channel is a cylinder double wall passage, and its cylinder double walled gap is 5mm;
Fill diameter 2mm gravel (14) particle in the water filling ring of cylinder bottom;
Water filling ring outer wall distributed aperture is the apopore (15) of 1mm.
5. the proving installation that is used for the judgement of soil layer settlement by soaking as claimed in claim 4, it is characterized in that: the height of water filling ring is 1.5cm.
6. the proving installation that is used for the judgement of soil layer settlement by soaking as claimed in claim 5 is characterized in that:
The cone point angle of conical probe (16) is 60 degree;
Awl point (17) is 2mm with the tangent circular cross section diameter of cone;
The cone bottom surface diameter of conical probe (16) is 4.5cm.
7. a proving installation according to claim 1 and 2 is judged the method for testing of soil layer settlement by soaking, it is characterized in that, comprises following test judgement step:
1) the proving installation top is applied a power, conical probe (16) at the uniform velocity is pressed in the soil, record the penetration resistance of a certain degree of depth place soil, calculate the intensity of this place's soil, wherein, said penetration resistance and soil shear strength relation are following: τ=aR-b;
Wherein, undrained shear strength τ and soil body ultimate bearing capacity q
uExist and concern τ=q as follows
u/ c, said c are coefficient, 2＜c＜3, and the cone floorage relation of said native state soil strength and conical probe (16) is: P=q
uS;
2) open the water filling switch, add water and make conical probe (16) position soil layer survey the saturated soil strength at this place to saturated back; And,
3) through the variation of intensity before and after the soil body immersion relatively, judge the settlement by soaking of soil layer, wherein, during P>=6MPa, be judged to be non-collapsible soil; During P＜6MPa, work as p/p
m, be judged to be collapsible soil at>=3.5 o'clock; During P＜6MPa, work as p/p
m, be judged to be non-collapsible soil at＜3.5 o'clock;
Wherein, said p is the native state soil strength, p
mBe the state of saturation soil strength.
8. the method for testing of judgement soil layer settlement by soaking as claimed in claim 7 is characterized in that, the injection speed when the injection speed of conical probe (16) is not soaked increases, and judges that then loess produces saturated yielding; If not adding the variation that injection pressure also can produce penetration resistance, then be judged to be self-weight collapse loess behind the soil layer chance water; If soil layer applying the variation that injection pressure just has penetration resistance, then is judged to be non-self-weight collapse loess.
9. the method for testing of judgement soil layer settlement by soaking as claimed in claim 7 is characterized in that, the said conical probe of control (16) probe into the degree of depth time, a hour step is controlled to be 50cm, wherein, the step is the spacing distance of two measuring points of conical probe when said.
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