CN103015438A - Collapsible loess subgrade landslide treatment method - Google Patents

Collapsible loess subgrade landslide treatment method Download PDF

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Publication number
CN103015438A
CN103015438A CN 201110293445 CN201110293445A CN103015438A CN 103015438 A CN103015438 A CN 103015438A CN 201110293445 CN201110293445 CN 201110293445 CN 201110293445 A CN201110293445 A CN 201110293445A CN 103015438 A CN103015438 A CN 103015438A
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pile
subgrade
loess
hammering
pipe
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CN 201110293445
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李应芝
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Abstract

The invention relates to the technical field of subgrade foundation treatment, in particular to a collapsible loess subgrade landslide treatment method which is characterized in that dry gravel is hammered into a pile by double pipes; the grain sizes of the gravel are 10mm to 30mm; the deviation between a pile pipe and the center of a hole site is no more than 2cm, the inclining degree of the pile pipe is no more than 1/400, the deviation of an effective pile length is no more than minus 10cm, and materials fed into a pile bottom are about 0.07m<3>; then hammering and compaction are carried out, an inner pipe is pulled out, and 0.14m<3> of gravel is added into an outer pipe; the hammering and the compaction step is repeated, until the pipe is pulled out and capping is carried out; and the ratio of piling and backfilling modified materials of loess to lime to water is 70: 20: 10. The collapsible loess subgrade landslide treatment method has the beneficial effects that the gravel pile can effectively eliminate the collapsibility of the loess foundation, a pile group and soil form the composite subgrade, so that the overall stability of the subgrade can be enhanced, the load bearing capability of the subgrade is improved, and settlement and uneven settlement are reduced.

Description

Collapsible loess subgrade landslide processing method
Technical field
The present invention relates to the foundation of road bed processing technology field, be specially a kind of collapsible loess subgrade landslide processing method.
Background technology
The formation reason of collapsible loess subgrade is under the selfweight stress effect of upper earthing, or under the selfweight stress and subsidiary stress acting in conjunction of upper earthing, natural porosity is large, water permeability is strong, under dry state, higher intensity and less compressibilty are arranged, the native rapid destruction of structure and generation significantly adds sinking after being subjected to water-soaked, and its intensity also reduces along with the loess of rapid reduction.The main cause that causes the Canal in Loess Area accident owing to Loess Collapsibility causes uneven settlement of foundation.In subgrade construction, often can run into collapsible loess and soft soil roadbed, if deal with improperly, will work the mischief to later operation, jeopardize traffic safety.Present processing method mainly is to prevent Mud pumping, makes the roadbed local subsidence cause asphalt surface course to occur cheating groove or forming the harm such as radial matrix zone of fracture, concrete slab fracture, also evenly distributes and bearing capacity at the load that improves road bed simultaneously.The present invention is according to engineering specifications, adopt broken stone pile to process the soft soil body of saturated yielding expansion loess, under the base integral distortion, compatibility of deformation by stake, soil, the rubble pile body that most of Load Transfer is large to rigidity, intensity is high, load on the soil body greatly reduces, and has improved the engineering property of saturated yielding ground.Simultaneously, broken stone pile can increase the loess compactness, and void ratio is reduced, thereby Compaction variables reduces compressibilty, improves anti-seismic performance, reduces sedimentation and differential settlement, shortens sedimentation period.
Summary of the invention
A kind of collapsible loess subgrade of the present invention landslide processing method, its purpose is to adopt the Dry Crushed Stone Piles processing method, by the compatibility of deformation of stake, soil, the rubble pile body that most of Load Transfer is large to rigidity, intensity is high, load on the soil body greatly reduces, and has improved the engineering property of saturated yielding ground.Simultaneously, broken stone pile can increase the loess compactness, and void ratio is reduced, thereby Compaction variables reduces compressibilty, improves anti-seismic performance, reduces sedimentation and differential settlement, shortens sedimentation period.
To achieve these goals, concrete technical scheme of the present invention is as follows:
One, Dry Crushed Stone Piles handling principle
(1), broken stone pile is to be filled into a hole after 10~30 millimeters rubble, lime, cement, river sand, water stirs by a certain percentage by particle diameter, with loess form compound foundation on every side, lime, cement absorb loess freedom on every side in conjunction with water, reduce the water content of water, the contraction of loess weakens settlement by soaking, and it is more closely knit that soil is tending towards.
(2), closely knit rubble pile body has replaced the soft loess identical with the pile body volume, because the loess around the intensity of stake and anti-deformation all are better than, so the performance by the common composite foundation that forms of loess between stake and stake improves, settling amount is also little than natural ground, thereby has improved resistance to overturning and the anti-destructive power of ground.
(3), when in cement loess, sinking to pile pipe, to producing very large horizontal extruding force around it, pile pipe is washed one's hair long-pending soil and is pressed to soil layer around the pile pipe equaling pile pipe in the ground, soil body void ratio is reduced, density increases, thereby eliminates collapsibility of loess, improves bearing capacity of foundation soil.
(4), the soil layer compactness increases, structural strength improves, and shows that mark passes through to hit number and increase, thereby improves the anti-liquefying power of soil layer itself; Simultaneously, broken stone pile is good drainage channel, can accelerate the dissipation of excess pore-water pressure that squeezing action produces, and reduces the amplitude that the crack water pressure rises, thereby improves the anti-liquefying power of inter-pile soil.
(5), learn according to simulated experiment, the modification stake is 4 times of stake diameter in the influence basin of loess, is 0.3 meter so select the diameter of stake, and the design pile spacing is 1 meter, and therefore the influence basin of stake has 0.2 meter overlapping, strengthens the stability of roadbed.
Two, Dry Crushed Stone Piles construction technology
(1), Scheme Choice: piling method is divided into vibrations pile and hammering pile two large classes.The vibrations pile is larger on the Nearby Structure impact, for guaranteeing the safety of Nearby Structure, selects the less hammering "forming column construction of impact.The hammering "forming column is divided into two kinds of single tube pile and two-tube piles.Comparatively speaking, less, the pile Shan, easy and simple to handle of two-tube pile waste is easy to control pile quality, so select two-tube hammering "forming column construction.
(2). the stake machine is selected with in place: select diesel hammer, elevating capacity 300KN, pile monkey 15KN.Pile pipe: casing adopts 6 millimeters seamless steel pipes of wall thickness, in join the core pipe, the short sword open steel of alloy boots pile top is installed before the core pipe.Protect simply directly 320 millimeters, core pipe 300 mm diameter.The core pipe adopts 1:5 rice, protects the long every joint of letter and is 1.5 meters.Outfit feed intake funnel and charging (feeding) equipment (trolley).For reducing system stake process to the disturbance of inter-pile soil, adopt interval stake mode processed to construct.Behind the pile-forming machine perching, pile pipe is most advanced and sophisticated aims at the good stake position of cloth, and guarantees that tip and the centrical deviation in hole are not more than 2 centimetres, and the pile pipe gradient is not more than 1/400.
(3), working procedure:
1., hammering pore-creating: the starting diesel pile hammer, inner and outer pipe is squeezed in the soil layer simultaneously to the degree of depth of design code, behind whole hole, (reach projected depth) and in time carry out clearly hole.
2., just throw " the seat end ".Pull up inner tube (being limited not block the outer tube dog-house), open material mouthful, rubble is packed in the outer tube; Close the dog-house door, put down on the inner tube pressure rubble face within the outer tube, pull up outer tube, the outer tube upper end is contacted with pile monkey with inner tube; The starting pile monkey, stake feeds intake for the first time and should lack in an end, fills out 0.5 trolley (about 0.07 cubic metre), then hammering compacting, this one-phase is named " the seat end ", can guarantee compactness long and an end.
3., make continuously stake.Pull up inner tube, add rubble in outer tube, feed intake is 1 trolley (about 0.14 cubic metre) at every turn, then hammering compacting, the compactness of assurance stake; Repeat above step, until tube drawing approaches the stake top.
4., the pile that binds.When system stake reaches the stake top, add rubble 2 times and add 1.5 trolleys at every turn at last, carry out hammering and be densified to ground.This one-phase is binding.Requirement effective length deviation must not be greater than-10 centimetres.
5., backfill sealing.Bind behind the pile in all piles hole, in time backfill Modified soil (loess that digs out in the pile hole, lime, water=70: 20: 10) compacting, dry-laid rubble jointing sealing.Repetitive operation is until outside the side slope saturated yielding landslide.
Beneficial effect of the present invention is the drainage channel effect of rubble pile body, and it is especially remarkable in cohesive soil to be that the broken stone pile method is processed saturated soft foundation, not limited by groundwater table; During pile, it is little to the disturbance of ground soil structure, structure to vibrate into the pipe method.After the system stake finished, massif convalescence weak point was conducive to procedure connection, reduce project cost.Broken stone pile can effectively be eliminated the loess foundation settlement by soaking, its job practices is because pile group and the soil body form composite road bed, can strengthen the resistance to overturning of roadbed, improve subgrade rating, reduce sedimentation and differential settlement, because the compressibilty of stake is lower than inter-pile soil body, the load major part that the outside is transmitted is subjected to by pile, only have the fraction load to directly act on the inter-pile soil body, roadbed stress is concentrated to stake to a certain extent.
The specific embodiment
Embodiment 1, process an engineering in conjunction with 312 national highway Pingliangs section collapsible loess subgrade landslide and do and specify
1, project profile
(1), this project is grown 600 meters, 120 kilometers of design speed per hours.This section is passed through with cutting, high about 30 meters of center excavation, and the left side barricade is high 7.5 meters, thick 3 meters.Be the secondary protection on the barricade, the one-level protection adds the support french drain for mortar flag stone, and the secondary protection is the skeleton bank protection.Found to have on the slabstone bank protection 4 in the crack of 8~52 mm wides behind the Practical Completion in 6 months, simultaneously barricade and bank protection boundary deformation of cylindrical.The interior main exposure stratum of this scope is loess, and it is lower to be land pebble, and lower again is sandstone, and lithology is described below:
(2), loess: 5~8 meters of thickness, local folder cement loess formation, hard plastic, II level soil, tool II level self-collapsibility, thick 4.6~7.5 meters of saturated yielding soil layer; Land pebble: thickness is greater than 5 meters, and composition is take sandstone, shale as main, mixed circle shape, particle diameter forms: 20-40 millimeter, 40-60 millimeter and account for respectively 40%, 15%, 5% greater than 60 millimeters persons, local folder circle gravel and gravel thin layer, in close, humidity, III level; Sandstone: compressive strength 50~150Kpa, shear strength 5~15Kpa, block structure, hardness is high.
(3), hydrogeological conditions: worker's point range bury of groundwater is greater than 20 meters; The earthquake motion peak accelerator is 0.4g (V level time macroseism).
2, processing scheme selection: piling method is divided into vibrations pile and hammering pile two large classes.The vibrations pile is larger on the Nearby Structure impact, for guaranteeing the safety of Nearby Structure, selects the less hammering "forming column construction of impact.The hammering "forming column is divided into two kinds of single tube pile and two-tube piles.Comparatively speaking, less, the pile Shan, easy and simple to handle of two-tube pile waste is easy to control pile quality, so select two-tube hammering "forming column construction.
3, the stake machine is selected with in place: select diesel hammer, elevating capacity 300KN, pile monkey 15KN.Pile pipe: casing adopts 6 millimeters seamless steel pipes of wall thickness, in join the core pipe, the short sword open steel of alloy boots pile top is installed before the core pipe.Protect simply directly 320 millimeters, core pipe 300 mm diameter.The core pipe adopts 1:5 rice, protects the long every joint of letter and is 1.5 meters.Outfit feed intake funnel and charging (feeding) equipment (trolley).For reducing system stake process to the disturbance of inter-pile soil, adopt interval stake mode processed to construct.Behind the pile-forming machine perching, pile pipe is most advanced and sophisticated aims at the good stake position of cloth, and guarantees that tip and the centrical deviation in hole are not more than 2 centimetres, and the pile pipe gradient is not more than 1/400.
4, working procedure:
1., hammering pore-creating: the starting diesel pile hammer, inner and outer pipe is squeezed in the soil layer simultaneously to the degree of depth of design code, behind whole hole, (reach projected depth) and in time carry out clearly hole.
2., just throw " the seat end ".Pull up inner tube (being limited not block the outer tube dog-house), open material mouthful, rubble is packed in the outer tube; Close the dog-house door, put down on the inner tube pressure rubble face within the outer tube, pull up outer tube, the outer tube upper end is contacted with pile monkey with inner tube; The starting pile monkey, stake feeds intake for the first time and should lack in an end, fills out about 0.07 cubic metre, then hammering compacting, this one-phase is named " the seat end ", can guarantee compactness long and an end.
3., make continuously stake.Pull up inner tube, add rubble in outer tube, feed intake is 1 trolley (about 0.14 cubic metre) at every turn, then hammering compacting, the compactness of assurance stake; Repeat above step, until tube drawing approaches the stake top.
4., the pile that binds.When system stake reaches the stake top, add rubble 2 times and add 1.5 trolleys at every turn at last, carry out hammering and be densified to ground.This one-phase is binding.Requirement effective length deviation must not be greater than-10 centimetres.
5., backfill sealing.Bind behind the pile in all piles hole, in time backfill Modified soil (loess that digs out in the pile hole, lime, water=70: 20: 10) compacting, dry-laid rubble jointing sealing.Repetitive operation is until outside the side slope saturated yielding landslide.
5, quality control and detection:
(1). the pile body continuity: during tube drawing as not pulling out the blank pipe phenomenon, but general avoid pile break guarantees that pile body is continuous, stake occurs and sharply sinks suddenly, or simultaneously run-off the straight, generally be the pile top splitting, stake is difficult to suddenly sink, the stake rebound is serious, extract the core pipe and see if there is rock dust, continue, hit 3~5 times continuously with pile monkey, getting rid of has the fritter rock to be clipped in the middle, if after repeatedly strike can not be broken up continuously, could confirm that this stake has reached designing requirement.
(2). pile body diameter and compactness: this worker puts to reduce the loess void ratio, and strengthening the compactness Compaction variables is main processing intent, so be controlled to be the master with amount of filler in the construction.By field trial, the graded broken stone coefficient of consolidation is 0.62.The closely knit rear theory of per 1 trolley rubble hammering pile length processed is: L=0.62 * 0.14/0.32 * π.For guaranteeing the pile body compactness, by 0.8 meter control of per 1 trolley pile pile body height, then safety factor is: η in the construction.
(3). quality examination: show by excavating test pile surrounding soil measurement: effectively pile body diameter is between 0.35~0.39 meter, and pile-forming effect is good, meets design requirement.
6, construction precautions:
The material of body of a pile particle diameter is 10~30 millimeters graded broken stones.It is higher that this worker puts natural Loess Moisture Contents, be generally about 15%, so the rubble water content is unsuitable large, generally selects the graded broken stone of water content 9%; Should do first 7~9 test piles before the construction, by testing definite construction parameter; Each working platform sequence of construction should be from both sides, advance to the centre gradually, and each level work platform excavates from bottom to top, determine the width of working platform according to field condition, and the gradient is milder should be wide, otherwise then be advisable can fill, move the diesel pile hammer auger; As when the blank pipe phenomenon occurring pulling out, must be in position tube sinking feeding is once or next door complement one pile again.
7, engineering effort:
(1) this project is driven piles 1236 altogether, amounts to long 7416 linear meter(lin.m.)s, and after completion of works experienced 3 rainy seasons, saturated yielding landslide phenomenon did not appear in this bank protection monolithic stability.
(2) this project is finished the pile body standard penetration test of 40 piles altogether, and every N63.5 value is all greater than 28, and average N 63.5 values are 31.According to the correction factor (looking into " worker China Democratic National Construction Association standard " α=1.05) of bar length and the relation between compactness, N63.5 〉=32.5 an o'clock pile body compaction rate reaches dense state, confirms that the whole closely knit quality of pile body is good.
(3) this project main purpose is to eliminate collapsibility of loess, Bearing Capacity of Composite Foundation is not made quantitative requirement, so only inspecting pile body by random samples carries out standard and passes through people test, check its compactness to be the drainage channel effect of rubble pile body, it is especially remarkable in cohesive soil to be that the broken stone pile method is processed saturated soft foundation, not limited by groundwater table; During pile, it is little to the disturbance of ground soil structure, structure to vibrate into the pipe method.After the system stake finished, massif convalescence weak point was conducive to procedure connection, reduce project cost.

Claims (3)

1. collapsible loess subgrade landslide processing method, it is characterized in that adopting the two-tube hammering pile of dryness rubble, ballast grain sizes is 10~30 millimeters, and the centrical deviation in pile pipe and hole is not more than 2 centimetres, the pile pipe gradient is not more than 1/400, and the effective length deviation must not be greater than-10 centimetres.
2. collapsible loess subgrade landslide processing method as claimed in claim 1, it is characterized in that: the two-tube hammering pile of described dryness rubble, feed intake about 0.07 cubic metre at the bottom of it, then hammering compacting, pull up inner tube, adding metaling in the outer tube is 0.14 cubic metre, hammering compacting repeating step, until tube drawing binds, pile backfill modified materials ratio is loess, lime, water=70: 20: 10.
3. collapsible loess subgrade as claimed in claim 1 landslide processing method is characterized in that: should do first 7~9 test piles before the construction, by testing definite construction parameter.
CN 201110293445 2011-09-28 2011-09-28 Collapsible loess subgrade landslide treatment method Pending CN103015438A (en)

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Application Number Priority Date Filing Date Title
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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN104213576A (en) * 2013-06-05 2014-12-17 中国石油天然气股份有限公司 Method for manufacturing large storage tank foundation on collapsible loess field
CN104746412A (en) * 2015-04-01 2015-07-01 贵州新联爆破工程集团有限公司 Construction method of collapsible loess embankment
CN112458809A (en) * 2020-10-19 2021-03-09 中交一公局集团有限公司 Treatment method for collapsible loess subgrade

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN104213576A (en) * 2013-06-05 2014-12-17 中国石油天然气股份有限公司 Method for manufacturing large storage tank foundation on collapsible loess field
CN104213576B (en) * 2013-06-05 2016-09-07 中国石油天然气股份有限公司 Large-scale Storage Tank Foundation preparation method on a kind of Site of Collapsible Loess
CN104746412A (en) * 2015-04-01 2015-07-01 贵州新联爆破工程集团有限公司 Construction method of collapsible loess embankment
CN112458809A (en) * 2020-10-19 2021-03-09 中交一公局集团有限公司 Treatment method for collapsible loess subgrade

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Application publication date: 20130403