Summary of the invention
Object of the present invention is providing a kind of equipment of indoor recovery undisturbed soil, solves and is difficult to gatherFor example carry out the problem of laboratory soil test under water without the soil sample such as cohesive soil, saturated soft clay.
Another object of the present invention is to provide the method that adopts this equipment to carry out undisturbed soil recovery.
The technical solution adopted in the present invention is to comprise rigidity reaction frame, rigidity reaction frame top peaceHydraulic jack is housed, and hydraulic jack below withstands on permeable lid surface, and permeable cover plate is close toThe first porous disc, the first porous disc is placed in rigidity floating ring inside, the first porous disc area and rigidityThe radial cross-sectional area of floating ring inwall is identical, and permeable cover plate can be withstood down by hydraulic jackMove, rigidity floating ring bottom is also provided with identical with the radial cross-sectional area of rigidity floating ring inwall theTwo porous discs, the second porous disc is installed in the ring flange of water container bottom and holds, and rigidity is floatingRing outer cover has water container, and rigidity floating ring stands on rigidity cushion block, on permeable cover plate, also pacifiesDisplacement transducer is housed, is used for testing the distortion of soil sample.
Feature of the present invention is also that the radial cross-section diameter of rigidity floating ring inwall is 60cm,Rigidity floating ring wall thickness 4cm; Described water container inwall radial cross-section diameter is 90cm, containsWater receptacle wall thickness 6cm. Permeable cover plate diameter 60cm, the permeable hole diameter on permeable cover plate0.6cm. The first porous disc and the second porous disc surface are posted work cloth, filter paper and gauze successively.
The present invention restores the method for undisturbed soil style, it is characterized in that: first gather undisturbed soil formulaSample, after for saturated soft soil sample, being dried, pulverizing, adds water its water content is slightly larger thanLiquid limit water content, is adjusted to stream and moulds shape, after built to rigidity floating ring, at outside shake tableUpper fully vibration is got rid of after internal porosity, and rigidity floating ring is lifted to water container; For nothingCohesive soil, is immersed in water, then directly fluidised form soil sample is poured into the steel being in placeProperty floating ring in, treat that open fire drains, floating surface can start test; Based on drawing up, standby sample is formerThe buried depth of beginning occurrence status and the vertical stress of estimation, calculate the target of sample in compacting barrelCompression height, and taking estimation vertical stress as reference, for weak soil, should design and be not less thanThe normal stress of 10 grades applies step number; For without cohesive soil, normal stress progression can suitably fallLow; Targeted compression height and design normal stress dual control factor can be proofreaied and correct mutually, and earth pillar has compressedAfter finishing, obtain the undisturbed soil style after restoring.
The invention has the beneficial effects as follows that whole sample making course simulated the actual origin cause of formation of most of soil,Unpowered impulse action or manually smear, multistage Slow loading can also recover without cohesive soil, fullPrototype structure state with the glutinous intergranular of soft clay sample soil; Ensure that sample meets original state.
Detailed description of the invention
Below in conjunction with the drawings and specific embodiments, the present invention is described in detail.
The present invention as shown in Figure 1, comprises rigidity reaction frame 1, and install at rigidity reaction frame 1 topHave hydraulic jack 2, hydraulic jack 2 below items are at permeable cover plate 3 surfaces, permeable cover plate3 are close to the first porous disc 4, the first porous discs 4 is placed in rigidity floating ring 5 inside, and first is permeablePlate 4 areas are identical with the radial cross-sectional area of rigidity floating ring 5 inwalls, and permeable cover plate 3 can quiltHydraulic jack 2 withstands and moves down, and rigidity floating ring 5 bottoms are also provided with rigidity floating ring 5 inwallsThe second porous disc 6, the first porous discs 4 and the second porous disc 6 that radial cross-sectional area is identicalBetween soil sample is housed, the second porous disc 6 is installed in the ring flange of water container 7 bottoms10 hold, and rigidity floating ring 5 outer cover have water container 7, because the soil body is saturated shape in experimentState, therefore sample around must all be immersed in water, rigidity floating ring 5 stands on rigidity cushion block 8On, on permeable cover plate 3, displacement transducer 9 is also installed, be used for testing the distortion of soil sample.Apparatus of the present invention are all furnished with porous disc up and down, therefore up and down can drainings, and the cover plate on topAlso being permeable, is mainly to prevent that under original state, the first porous disc 4 floats, in addition due toOne porous disc 4 is thinner, and permeable cover plate 3 also plays the effect of transmitting and spreading top loading force.As shown in Figure 2, the radial cross-section diameter of rigidity floating ring 5 inwalls is 60cm, rigidity floating ring5 wall thickness 4cmm; Water container 7 inwall radial cross-section diameters are 90cm, water container 7Wall thickness 6cm. As shown in Figure 3, permeable cover plate 3 diameter 60cm, on permeable cover plate 3 thoroughlyWater hole diameter 0.6cm. The first porous disc 4 and the second porous disc 6 surfaces post successively work cloth,Filter paper and gauze. The combination of geotextiles, filter paper, gauze is mainly to prevent that in the soil body, fine grained existsLoss in consolidation process.
The present invention obtains the method for undisturbed soil experiment style, it is characterized in that: first gather original stateSoil, after for saturated soft soil sample, being dried, pulverizing, adds water its water content is slightly larger thanLiquid limit water content, is adjusted to stream and moulds shape, after built to rigidity floating ring 5, at external vibrationOn platform, fully vibration is got rid of after internal porosity, and rigidity floating ring 5 is lifted to water container 7;For without cohesive soil, be immersed in water, then directly fluidised form soil sample is poured into and is installed toIn the rigidity floating ring 5 of position, treat that open fire drains, floating surface can start test; Based on drawing upThe standby buried depth of the original occurrence status of sample and the vertical stress of estimation, calculate compacting barrel pilot scaleThe targeted compression height of sample, and taking estimation vertical stress as reference, for weak soil, should designThe normal stress that is not less than 10 grades applies step number; For without cohesive soil, normal stress progression canSuitably reduce; Targeted compression height and design normal stress dual control factor can be proofreaied and correct mutually, earth pillarAfter compression, obtain the undisturbed soil style after restoring.
This invention will provide a set of complete technology path, and develops relevant device, for chamberInterior recovery undisturbed sample and batch are prepared soil test sample, concrete equipment design and test streamDetails are as follows for journey:
1, develop indoor recovery undisturbed sample main equipment. This equipment has following two features:1, the design of rigidity floating ring 5 makes the soil body can two-sided consolidation draining in compression process, changesBe apt to sample internal penetration environment, accelerated the consolidation rate of sample, and 5 conducts of rigidity floating ringA movable part, dismounting is convenient, for testing the collection of building and test rear sample of front soil sampleProvide convenience; 2, the design of permeable system will be accelerated discharging consolidation speed on the one hand, anotherAspect also will ensure that drainage rates is even as much as possible in sample inside, avoids excellent in compression processThe formation of gesture percolation path and fine grain loss have designed geotextiles, filter paper, gauze for this reasonAnd a set of pumping equipment such as permeable cover plate 3.
2,, for saturated soft soil sample, after being dried, pulverizing, add water and make its water content slightlyBe greater than liquid limit water content, be adjusted to stream and mould shape, after built to diameter 60cm, high 50cmLarge-scale floating ring formula rigidity bucket, in rigidity floating ring 5, abundant vibration row on outside shake tableExcept after internal porosity, rigidity floating ring 5 is lifted to water container 7; For without cohesive soil (powderSoil, sandy soil) process is simpler, is immersed in water, directly fluidised form soil sample is filled with afterwardsEnter in the rigidity floating ring 5 being in place, treat that open fire drains, floating surface can start test,Ensure saturated, loose characteristic under sample original state.
3, based on the standby buried depth of the original occurrence status of sample and the vertical stress of estimation of drawing up, meterCalculation draws the targeted compression height of sample in compacting barrel, and taking estimation vertical stress as reference.For weak soil, should design and be not less than the normal stress of 10 grades and apply step number, former because: weak soilBelong to cohesive soil, be that without the difference of cohesive soil maximum soil sticks the cementation of intergranular with sand etc.And between particle in conjunction with the interaction of water, design multistage Slow loading and simulated on the one hand weak soilIn history of forming, burden pressure progressively increases and the process of fixed compression, on the other hand canReduce as much as possible glutinous intergranular texture characteristic in original state weak soil; For without cohesive soil, without pimpled rubberKnot and good penetrability, normal stress progression can suitably reduce. Normal stress applies principle:
1), undisturbed soil is composed and is deposited stress state: the soil body has difference with its stress distribution of change in depth,Therefore first stress state is deposited in undisturbed soil tax needs to determine in conjunction with the sampling depth of test sample book,This index changes, and taking the soil under water of 30m buried depth as example, its original vertical should soPower is about 240kPa, and this index is the vertical stress under original occurrence status.
2), method phase loading stress: method phase loading stress estimates the original vertical stress obtaining
3), multi-stage loading: in fact the formation of the soil body experienced the very long period of history, and rightIn weak soil sample, apply suddenly very large normal direction load can cause sample extrude, fixedEvenly etc. Therefore, in order to simulate the origin cause of formation of the soil body, taking the original vertical stress estimated as criterion,Adopt even or inhomogeneous method for arranging, design multiple-stage method is to stress loading scheme. Technology moreMuch better, but must consider test efficiency, through overtesting, adopt 10 grades to fit for soft clayEnough satisfy the demands by performance. Better without cohesive soil permeability, stress progression can suitably reduce, andWithout fixed number.
4), targeted compression amount: before normal stress loads, the sample in rigidity floating ring 5 is veryLoose, can test its natural dry density, natural porosity according to a small amount of undisturbed soil gatheringDeng. Index accordingly, we can calculate the dry ground weight that 20cm earth pillar is corresponding, by itAdd water and build to rigidity floating ring 5 (before test, sample is loose, is highly necessarily greater than 20cm,For example 25m). So, our target of test is exactly at original vertical stress, designs multistageLoading scheme, is compressed to earth pillar near object height 20cm. Why can not be completely etc.In 20cm, be mainly that the soil body has certain structural, reduction undisturbed soil that can not 100%.
So-called dual control is exactly the mutual correction between object height and compression stress. Based on soil body thingReason characterisitic parameter, computing method is to the object height under loading stress condition. With conventional compression testCompare, targeted compression height and design normal stress dual control factor can be proofreaied and correct mutually.
4, after earth pillar compression, unload the permeable cover plate 3 of upper surface and the first porous disc 4.For weak soil sample, now also can adopt miniature cross plate shearing instrument, miniature static penetrometer etc.Equipment on weak soil surface and different depth carry out indoor in-situ test, obtain sample mechanics parameter,And contrast test sample preparation quality with surveying in situ data.
5, need according to follow-up test, choose the thin-wall seamless stainless steel tube of suitable dimension, withSlowly the mode of static pressure gathers cylindric soil body sample from rigidity floating ring 5, fully after sealingProperly preserve, adopt for laboratory soil test.
The present invention is one and simulates the undisturbed soil origin cause of formation and reduce its actual occurrence status, in batches preparationThe technical scheme of the required soil sample of laboratory soil test. Wherein, the implementing procedure of soft clay is more multipleAssorted, set forth technical scheme below as an example of certain clayey soil example, part emphasis step be aided with picture orIllustration.
1, based on the basic physical property of a small amount of undisturbed soil test weak soil, mainly comprise dry density,Natural moisture content, liquid plastic limit and void ratio; Meanwhile, need obtain the sample collection degree of depth, roughly(for example vane-shear is strong for the partial parameters of normal stress interval and field In situ testDegree, static sounding data).
2, according to targeted compression earth pillar height, calculate the quality of required soil sample, stream is moulded shape soil creamModulation, rigidity floating ring 5 in model build and emptying sample in pore.
3, adopt sample making apparatus, testing equipment figure is shown in Fig. 1. According to targeted compression height and estimateThe virgin state of stress dual control standard of calculating, designs multiple-stage method to stress loading consolidation test scheme,By the relation of effective stress and void ratio, calculate compression goal height corresponding to normal stress. RightIn saturated clay and silty clay, because its infiltration coefficient is low, fixed compression process should accomplish to delaySlow pressurization, fully fixed, control step by step, revise step by step, make the cementing pass of the glutinous intergranular of the soil bodySystem recovers as far as possible, reduces and reinvents the impact of Structure of Soft Clay on sample quality; Glutinous poly-without cohesive soilPower can be ignored, and does not have chemical bond good penetrability in addition between particle, and stress loading level can be suitableReduce, consolidation time also significantly shortens, and process of the test is relatively simple.
4,, for weak soil sample, can carry out indoor micro In situ test: after fixed,The permeable cover plate 3 of removal and the first porous disc 4, carry out miniature former at specimen surface and different depthPosition soil test, for example miniature vane shear test and miniature cone penetration test.
5, adopt seamless thin wall steel pipe to gather undisturbed sample: must avoid dynamic action to examinationThe disturbance of spline structure and destruction. Adopt multiple thin-wall steel tube samplings (wall thickness should be less than 1mm),Be cut into some sections according to the complete earth pillar height of compression by isometric steel pipe, be arranged on earth pillarSide, for avoiding soil compaction effect, between round steel pipe, retain 2cm distance between left and right, after by oilPress jack 2 that steel pipe is slowly pressed in earth pillar, all steel pipes of rear taking-up, obtain soil testRequired original state weak soil sample.
Steel pipe sizes need be chosen according to the purposes of follow-up test, for example, for triaxial test,Sample common-use size can be divided into: Φ 10.1cm*H20.0cm (greatly), Φ 6.18cm*H12.0cm(in), three kinds of specifications such as Φ 3.91cm*H8.0cm (little), large-scale and medium-sized specification sample is adoptedCollection can be processed the steel pipe of internal diameter coupling by custom-made; Small sample, because size is less, can adoptLarge-scale specification gathers after steel pipe collection, according to earthwork test rule SL237-1999, with geotechniqueCutter cuts into target size sample.
Than prior art, advantage of the present invention is embodied in:
1, whole sample making course has been simulated the actual origin cause of formation of most of undisturbed soils, unpowered pulseAct on or manually smear, it is glutinous that multistage Slow loading can also recover weak soil sample soil as much as possibleThe prototype structure state of intergranular;
2, the sample that this invention makes is K0 consolidated earth mass sample truly, without meterCalculate hypothesis, meet the stress state of undisturbed soil completely;
3, can the larger complete sample of preparation size, therefore can carry out part little (micro-) typeIndoor In situ test;
4, realized the batch preparation of geotechnical sample, what ensured the parallel contrast of test result canOperability.
The present invention will be described to use specific embodiment below: