CN202430702U - Probe based on multifunctional piezocone penetration test - Google Patents

Abstract

The utility model discloses a probe based on multifunctional piezocone penetration test, and relates to a probe based on multifunctional CPTU (piezocone penetration test) for measuring lateral pressure coefficient of soil. A sounding probe body is connected with a feeler bar (6), a three-component seismic detector (5) is disposed on the upper portion of a lower half section of the probe body, an inclinometer (4) is arranged on the lower portion of the three-component seismic detector (5), a friction drum (3) is positioned below the inclinometer (4), the probe body (1) is connected to the lower side of the friction drum (3), and a pore pressure filter ring (2) is positioned at a joint of the friction drum (3) and the probe body (1). The lateral pressure coefficient is directly obtained according to a measurement value of normalized side-wall frictional resistance (fs/) and a predicted value of over-consolidation ration (OCR), the OCR can be determined by the aid of multifunctional CPTU in-situ test technology, and correlation between normalized net tip resistance and the over-consolidation ration is reliable. Besides, the probe implementing the method has the advantages of normal position, speediness, accuracy, economical efficiency and the like.

Description

Press static sounding probe based on multi-functional hole

Technical field

The utility model relates to a kind of probe of the mensuration earth lateral pressure coefficient based on multi-functional CPTU, belongs in the field of civil engineering a kind of new earth lateral pressure coefficient and measures probe.

Background technology

Static sounding technology (CPT) is meant the sounding rod indentation test soil layer that utilizes pressure apparatus will have contact probe; Through the native static point resistance of measurement system test, sidewall frictional resistance etc.; Can confirm some basic physico mechanical characteristic of soil, like the modulus of deformation of soil, the allowable bearing of soil etc.The static sounding technology is the history in existing more than 80 year so far.The extensive use static sounding has partly or entirely replaced probing and the sampling in the engineering investigation in the world.China at first succeeded in developing the electric measuring type static sounding and is applied to engineering investigation in nineteen sixty-five.It is the novel in-situ testing technique that rises in the world the eighties in 20th century that static sounding technology (hereinafter to be referred as multi-functional CPTU) is pressed in the multi-functional hole of modern digital formula; Compare with the quiet spy of single doube bridge that China is traditional, have theoretical system, multiple functional, advantages such as parameter is accurate, precision is high, good stability.Both can accurately divide soil layer, carry out the great soil group differentiation with the sensitivity that press in ultra hole; Can ask for native original position state parameter, the coefficient of consolidation, transmission coefficient, kinetic parameter, structural parameters, foundation bearing characteristic etc. again, be used widely in the civil engineering design abroad.

Static earth lateral pressure coefficient (K _o) be a very important parameter in the geotechnical engineering, all need Stationary side pressure coefficient accurately like the stress state in definite place, calculating earth pressue at rest, the pore water pressure of earth dam construction period and stake side direction bearing capacity calculation or the like; Also to use Stationary side pressure coefficient accurately in the lining cutting in the diaphragm wall in underground construction, tunnel and the underground structures such as landfill pipeline in the soil design simultaneously.Construction along with subway, light rail; Relate to the soil pressure problem of a lot of underground structures; And the Stationary side pressure coefficient of each soil layer can reflect that level is to the variation of stress in the ground; Can directly extrapolate the soil pressure that acts on the soil-baffling structure thing thus and distribute and reliability, so generally all requires to test Stationary side pressure coefficient K in the subway, light rail, base pit engineering prospecting _oValue.But be that it all is one of the most difficult parameter of accurately measuring through soil test or conventional in-situ test.Therefore, the sidewall frictional resistance that applicable holes presses static sounding institute directly to record reasonably adopts the hole to press existing formula is revised, and proposes to consider that effectively upward the static earth lateral pressure coefficient Forecasting Methodology that is suitable for underground construction of earthing pressure is highly significant.

Summary of the invention

Technical problem: the technical problem that the utility model will solve is the uncertainty that exists to the static earth lateral pressure coefficient the whole bag of tricks of domestic existing mensuration, proposes a kind of based on multi-functional hole pressure static sounding probe.

Technical scheme: the utility model is pressed static sounding probe based on multi-functional hole, and its top connects feeler lever; Top at this probe lower semisection is provided with 3-component earthquake detector; Bottom at 3-component earthquake detector is provided with inclinometer; Friction cylinder is positioned at the below of inclinometer; Below friction cylinder, be connected with conical probe, hole press filtration ring is positioned at the junction of friction cylinder and conical probe, and the feeler inspection probe is identical with the feeler lever diameter.

The cone angle of conical probe is 60 °, and the awl basal cross section is long-pending to be 10cm ²The friction cylinder surface area is 150cm ²

Hole press filtration ring thickness is 5mm, and the end area ratio that do not wait of probe is 0.8.

The utility model presses the method for the mensuration earth lateral pressure coefficient of static sounding probe to be to adopt normalization sidewall frictional resistance (f based on multi-functional hole _s/ σ ' _Vo) predicting earth lateral pressure coefficient with overconsolidation ratio OCR, overconsolidation ratio OCR is by the clean static point resistance q of normalization _NetCalculate, its relational expression can be expressed as:

$\mathrm{OCR}=k\left(\frac{q_t-{\mathrm{\σ}}_{v0}}{{\mathrm{\σ}}_{v0}^{\′}}\right)$

In the formula, q _Net=(q _t-σ _V0) be clean static point resistance; σ _V0Be vertical total stress; q _tFor press the static point resistance=q that revises through the hole _c+ u (1-a), q _cBe the actual measurement static point resistance, u is the hole pressure value that the CPTU probe measures, and a is a test parameters for probe does not wait end area ratio, k.

To Jiangsu typical case's clay court, the excursion of k is between 0.37～0.45.

The Stationary side pressure coefficient of soil is defined as level to effective stress and vertical ratio to effective stress, and expression formula is following:

K ₀=σ′ _h0/σ′ _v0

In the formula, σ ' _HoFor level to effective stress; σ ' _VoFor vertically to effective stress.As far as normally consolidated soil, formula capable of using is calculated:

K ₀＝1-sinφ′

Concerning loading-off-load had the historical soil of simple stress, formula capable of using was calculated:

K ₀＝(1-sinφ')OCR ^sinφ′

In the formula,

is native effective angle of inner friction; OCR is native overconsolidation ratio.Overconsolidation ratio OCR is by the clean static point resistance (q of normalization _Net) calculate.Its relational expression can be expressed as:

$\mathrm{OCR}=k\left(\frac{q_t-{\mathrm{\σ}}_{v0}}{{\mathrm{\σ}}_{v0}^{\′}}\right)$

In the formula, q _Net=(q _t-σ _V0) be clean static point resistance; σ _V0Be vertical total stress; q _tFor press the static point resistance=q that revises through the hole _c+ u (1-a), q _cBe the actual measurement static point resistance, u is the hole pressure value that the CPTU probe measures, and a is a test parameters for probe does not wait end area ratio, k.This expression formula draws based on the high pressure consolidation test of cohesive soil, the test of triaxial stress path and other laboratory test.

Beneficial effect: the said method based on multi-functional CPTU probe and mensuration earth lateral pressure coefficient of the utility model is the on-the-spot earth lateral pressure coefficient new method of confirming, this method is to adopt normalization sidewall frictional resistance (f _s/ σ ' _Vo) predict earth lateral pressure coefficient with overconsolidation ratio OCR, be the empirical formula that on the basis of a large amount of different places of statistics CPTU test result, proposes.This method is particularly useful for the prediction of Jiangsu normal consolidation～slight overconsolidation earth lateral pressure coefficient in the medium overconsolidation stickiness soil layer.

Description of drawings

Fig. 1 is the multi-functional CPTU probe schematic diagram that the utility model adopts;

Wherein have: conical probe 1, hole press filtration ring 2, friction cylinder 3, inclinometer 4,3-component earthquake detector 5, feeler lever 6.

Fig. 2 is that the utility model is by sidewall frictional resistance (f _s) and overconsolidation ratio (OCR) confirm earth lateral pressure coefficient (K _o) sketch map.

The specific embodiment

The said multi-functional hole of the utility model presses the static sounding probe upper semisection to connect feeler lever; Adopt truck hydraulic pressure injection system will connect in the probe injection soil layer of feeler lever, be provided with 3-component earthquake detector, be provided with inclinometer in the bottom of 3-component earthquake detector at this probe lower semisection; Friction cylinder is positioned at the below of inclinometer; Middle part at friction cylinder is provided with pore water pressure sensor, below friction cylinder, is connected with probe, and hole press filtration ring is positioned at the junction of friction cylinder and probe.The cone angle of probe is 60 °, and the awl basal cross section is long-pending to be 10cm ², the friction cylinder surface area is 150cm ²

Earth lateral pressure coefficient (K _o) and CPTU sidewall frictional resistance (f _s) have dependency relation, and in different great soil groups, the hole pressure reduction that produces in the CPTU penetration process is very not big.The utility model has proposed based on overconsolidation ratio OCR and normalization sidewall frictional resistance (f based on Jiangsu typical case's clay court CPTU test data _s/ σ ' _Vo) prediction earth lateral pressure coefficient (K _o) sidewall frictional resistance force method, as shown in Figure 2.

Overconsolidation ratio OCR is by the clean static point resistance (q of normalization _Net) calculate.Its relational expression can be expressed as:

$\mathrm{OCR}=k\left(\frac{q_t-{\mathrm{\σ}}_{v0}}{{\mathrm{\σ}}_{v0}^{\′}}\right)$

In the formula, q _Net=(q _t-σ _V0) be clean static point resistance; σ _V0Be vertical total stress; q _tFor press the static point resistance=q that revises through the hole _c+ u (1-a), q _cBe the actual measurement static point resistance, u is the hole pressure value that the CPTU probe measures, and a is probe effective area ratio, and k is a test parameters.To Jiangsu typical case's clay court, the excursion of k is between 0.37～0.45.

The utility model is with the CPTU result of the test of Jiangsu typical case clay court, measures the level that acts on the CPTU friction cylinder to stress, sets up measuring value and in-situ horizontal effective stress σ ' then _HoBetween rule-of-thumb relation, the sidewall frictional resistance estimation horizontal effective stress of a kind of method with CPTU probe proposed, as shown in Figure 2.There is sidewall frictional resistance (f in this method _s) accuracy problem that measures and the problem that need estimate OCR in advance.And arrive medium overconsolidation clay to Jiangsu normal consolidation～slight overconsolidation, and can adopt multi-functional CPTU in-situ testing technique to confirm preconsolidation pressure or OCR, wherein adopt the dependency relation of clean static point resistance of normalization and overconsolidation ratio to confirm comparatively reliable.The relational expression of existing clean static point resistance of normalization and overconsolidation ratio can be used for confirming the stress history of cohesive soil, and existing place test result shows that the excursion of test parameters k is between 0.37～0.45.

Claims (3)

1. press static sounding probe based on multi-functional hole for one kind, it is characterized in that connecting feeler lever (6) on this feeler inspection probe top; Be provided with 3-component earthquake detector (5) on the top of this probe lower semisection; Be provided with inclinometer (4) in the bottom of 3-component earthquake detector (5); Friction cylinder (3) is positioned at the below of inclinometer (4); Be connected with conical probe (1) in the below of friction cylinder (3), hole press filtration ring (2) is positioned at the junction of friction cylinder (3) and conical probe (1), and the feeler inspection probe is identical with feeler lever (6) diameter.

2. according to claim 1 the cone angle that it is characterized in that conical probe (1) is 60 ° based on multi-functional hole pressure static sounding probe, and the awl basal cross section is long-pending to be 10 cm ²Friction cylinder (3) surface area is 150 cm ²

3. according to claim 1ly press static sounding probe based on multi-functional hole, it is characterized in that hole press filtration ring (2) thickness is 5 mm, it is 0.8 that probe does not wait the end area ratio.

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