关于半刚性桩复合地基若干问题的研究

1、Concerning the research of the foundation some problems of a compound of half(1.The University of Zhejiang civil engineering department, Hangzhou in Zhejiang 310027;2.Too the principle work university civil engineering department, the mountain west is too original 030024Summary:Aim at the rigid and

2、compound foundation of half in the cement soil stake and CFG stakes of the extensive usage at the engineering practices to moderate some problems within researches, for example a stake that transforms the amount of mold, the cement soil stake and CFG stake soil should exertive coefficient , the ceme

3、nt soil stake and the compound foundation quiet lotus of the CFG stakes of dints carry on trial method etc.Combine some concrete engineering, carried on to experiment the research and theories analysis to these problems;Put forward the cement soil stake transform amount of mold and a soil should the

4、 dint develop the coefficient of suggestion take the value and solve the mat layer constitution and the mat layers to compress the quantity to the correction method that the engineering practice the influenceKeyword:Cement soil stake;Transform the amount of mold;CFG stake;A soil should dint exertive

5、 coefficient;The quiet lotus carries to experimentMedium diagram classification number:TU473.1 Cultural heritage marking code:A The cement soil stake and CFG stakes are a compound of extensive applied half foundations currently, among them, the cement deep agitation stake has already woven into the

6、People's Republic of China profession standard the building foundation processing technical specification ( the JGJ79 91), the national standard of the CFG stake also in the establishment.The author met some problems in be engaged in the design of the cement soil stake, CFG stake, examine, study

7、, among them, some problems really settle and transform the calculation to have the importance influence towards reuniting the foundation loading dint, but have no explicit provision in the norm, for example:A body cement soil transforms the amount of mold, a soil of should dint exertive coefficient

8、 and compound the foundation calms down to carry the lotus to experiment medium constitution etc. of the mat layer.This text knots the cooperator own measure the data and the test data that other people announce already actually, carry on the study to these three problems1 The cement soil transforms

9、 the amount of moldThe cement soil transform the amount of mold E50 is should the dint press the strength for 50% anti- of mow the line mold quantity.Six 贻 hero etc.1 suggestion E50=(120-150) qu, ZHANG TU3 QIAO22 suggestion consider the spot tries the stake with indoor experiment the result of margi

10、n, the spot cement soil transforms the amount of mold E50=(60-90) qu, reckon according to the above relation, qu=0.6-0.4 MPas, E50=36-600 MPas, this result is lower than true value of transform the amount of mold.The formula that some person put forward is an E50=(150-390) qu.Author the data that th

11、e adduction domestic announce already from indoor experiment, the spot tests to analyze three aspects to carry on the study to the amount of mold of the cement soil with theories.1.1 Indoor experiment the king to wait with an eastern exposure3 measuresed the fp- a relation curve that the cement soil

12、 strength experiment, according to the curve anti- calculate a cement soil to transform the amount of mold,such as table,1 show.From the table 1 of result it is thus clear that E50/ qu=141-196, be worth to 173 equally. The table 1 cement soils transform the amount of moldThe anti- presses the streng

13、th/ MPa E50/ MPa E50/ qu remarks1.601.801.341.38 315254234247 196141175179 Indoor go together with the ratioIndoor go together with the ratioA body samplingA body sampling1.2 The spot measures the segment actually after the 伟 passes to lay the contingency to spread the feeling machine in a body, mea

14、sure the quiet lotus carry to experiment in a body stalk dint and the number of the contingencies, transforming the amount of mold,such as table, calculatingly 2 show. The mold quantity with should the relation of the dint,such as figure,1 show, can see from the curve in diagram, the cement soil tra

15、nsforms the amount of mold with should the dint level increment but present to let up the trend.1# E50=1120 MPas,2# E50=1150 MPas, indoor experiment the result as the w=15%, qu=1.69 MPas, can get from here:E50=(662-680) qu.The table 2 cement soil calculations transform the amount of mold160 remarkse

16、s of p/ kPaE/MPaE/MPa 15401600 12241406 9801300 748995 675557 570- 1# Pu=160 kNs2# Pu=216 kNs1.3 Carry to experiment the result according to a quiet lotus anti- calculate the stake to transform the amount of mold in a quiet lotus carry experiment, if neglect the stake to carry to under lie the layer

17、 to stab to go into, the stake sinks to decline sse two parts that is measured the e and stakes by a the compression of the body to carry the soil to constitute namely:S= the e+ sse(1)In the type:. A go into type(1),. (2) Among them, the is an influence coefficient that reflects a body stalk dint to

18、 deliver, supposing the stake to carry should dint is a crest should dint of 10%, a body should the dint press the straight line variety, =0.55, according to segment after the test of the wei , the powder that 12.5-15.0 ms grow spray a =0.3. Mix blend a quiet lotus to carry to experiment according t

19、o the cement that the some engineering do, a long 14.0 ms, a path 500 mms, Qu=400 kNs, be the Q=200 kNs, take the =0.3, s=2.09 mms, a go into type of above data:(2).That extreme limit loading dint is a 2 MPas, E50=1025 qus. According to the white virtuous the cement that permit to do mixs blend a qu

20、iet lotus to carry to experiment, a path 500 mms, a long 7.5 ms, a lotus carries for the 0.9 MPas, S=2.46 mms, because the stake grow shorter, take the =0.5, the generation goes into the type:(2).The extreme limit lotus of the stake carries for the 1.8 MPas, E50=762 qus. Pass the above analysis, get

21、 indoor experiment the E50=(141-196) qu, the spot test E50=(762-1025) qu.Because theories analysis the qu calms down for the spot the lotus carries to experiment the result, if consider indoor go together with to have a competition to check the result and experiment on the scene the result specific

22、value is 1.5, carry on theories is analytical as a result correction, then E50=(508-683) qu and test on the scene the result and then relatively near to.The basis is above analytical, the suggestion E50=(500-650) qu.2 The compound foundation loads the dint mechanism and loads the dint calculation fo

23、rmula Compound foundation according to line to strengthen the body just the degree can is divided into rigid stake of a compound foundation and halfs compound foundation.A compound foundation mainly has the sand stake, the crushed stones stake, a compound of half foundation mainly has the cement soi

24、l stake and CFG stake etc.s. Construct the foundation processing technical specification ( JGJ79-91)5 are as follows for the sand stake of and the compound foundation loading dint calculation formula of the cement soil stakes: Sand stake (3) A of the cement soil (4) In the type:Fsp, the k loads the

25、dint standard for the compound foundation value;The m is an area displacement rate;The Ap cuts the area for the stake;Be worth for the loading dint standard of a soil;Load the dint standard value for a natural foundation;Fp, the k loads the dint standard value for a body unit area;Be worth toward th

26、e loading dint standard for a 竖 ;The loads the dint to fold to reduce the coefficient for a soil, being the stake to carry to is commendable for soft soil hour 0.5-1.0, be the stake to carry to is commendable for hard soil hour 0.1-0.4, is commendable while being to take no account of a soil functio

27、n 0. Contrast type(3) and type(4) it is thus clear that, a compound foundation loading dint is a loading the dint and a soils load the dint to add mutually of result, but rigid and compound foundation of half at add mutually want to be to the stake the soil carries on fold to reduce, folding to redu

28、ce the coefficient to take 0-0.1, the size is decided by a soft hard degree for carrying the soil.Under the rigid foundation function, this kind of considers to certainly have the its teachings reason of, but, because of the compound the foundation established the 150-300 mms thick freestone mat lay

29、er in the foundation bottom, a head can heading up to stab to go into, making a local product living opposite transform, the loading dint of the soil get exertive, combine the curve of P- s of the stake and the curve of P- s of the soils to carry on the discussion below. Engineering 1 of the enginee

30、ring stake and stake soil carry the lotus to experiment the curve of P- s,such as figure,2 show, carry the lotus plank diameter 1050 mms.From the diagram it is thus clear that, the curve of P- s of the stake at up, the curve of P- s of the soil at under, if the stake and soils sink to decline equal,

31、 then be the loading dint of the stake to be equal to the standard to be worth the 200 kNs, to should the loading dint of the soil is a 78 kNs, developping the loading dint standard of the soil to be worth 49% of the 160 kNs only;When the loading dint of the stake is equal to the extreme limit to be

32、 worth the 400 kNs, the loading dint of the soil for 290 kNs, attain 90% that a soil loading dint extreme limit is worth the 320 kNs;If to make the loading dint of the stake and the loading dint of the soil attain their standard value at the same time, then the soil sinks to decline and should compa

33、re the stake to sink to decline the big 3.7 mms.From the above analysis it is thus clear that, because stake just the degree compares the soil just the degree is big, sinking to decline in the homology under, the loading dint of the stake is exertive the degree compares the loading dint of the soil

34、exertive the degree is high, the lotus carries more big this kind of phenomenon more not obvious, be attain When the extreme limit lotus carry, this kind of difference is small. Figure 3 show the relation that carries to compress the quantity and a soil with the mat layer to carry to compress the of

35、 quantity with the mat layer up the lotus for a lotus of stake.Because the stake crest lotus carry should the dint concentration, a head must stab to go into toward the mat layer, if the k means the stake, a soil loading dint the exertive level sinks to decline the term of validity at the same time

36、mutually, the k means that a head stab into the quantity, then being the k= the k, the loading dint of the stake and a soil is exertive at the same time;When the k< the k, the loading dint of the stake is been first in the loading dint of the soil exertive;When the k> the k, the loading dint o

37、f the soil is exertive first in the loading dint of the stake.Therefore, speak theoretically can with the thickness of the appropriate adjustment mat layer and press solid method make the loading dint of the stake and a soil synchronous exertive, but hard to do in the engineering physically, also ha

38、ve no necessity.As long as pass the adjustment of the mat layer, make the extreme limit appearance next and can near to with the loading dint of a soil full exertive can.From here analytical, take the to take 0.75-1.0 more steady, request the strict building to take the small value towards transform

39、, transform to request the not strict building to take the big value.（The figure 1 lotuses carry to measure the relation figure 2 engineerings 1 stake and stake soils with mold to calm down to carry the lotus to experiment the P- s curve figure 3 lotuses to carry to compress the quantity relation wi

40、th the mat layer 4 engineerings of figure 2 calm down to carry the lotus to experiment the P- s curve figure 5 experiment equip to signal hint the figure 6 quiet the lotus carries to measure actually with revise curve）3 The compound foundation calms down to carry the lotus to experiment 3.1 The comp

41、ound foundation calm down carry the lotus experiment medium of not normally the phenomenon is in reunite foundation calm down carry lotus experiment, for the sake of the reflection the foundation is subjected to the dint function physically, must do the 15-30 mms thick freestone mat layer while carr

42、y the lotus plank, best with design of the mat layer thickness homology.Because the compression and a heads of the mat layer stab to go into toward the mat layer, usually resulting in compound foundation calm down carry the lotus to experiment to sink to decline to be partial to greatly.When press o

43、pposite transform the value certain compound foundation loading dint, this kind of result will get a low loading dint.At the same time, appear a kind of falsely often phenomenon, carry the function in the same lotus under, reunite the foundation to sink to decline to compare the single stake to sink

44、 to decline to still want greatly.Figure 4 show is an engineering 2 of calm down and carry the lotus experiments the curve, a long 14 ms, a path 500 mms, from the diagram it is thus clear that, the curve of P- s that reunites the foundation to sink to decline the curve of P- s to locate the single s

45、take is under, just arrive to near to the extreme limit lotus carry the compound foundation of curve of P- s just return to the curve of P- s of the single stake above.This is because of the first half segment in the P- s curve, sink to decline the s smaller, the compression quantity of the mat laye

46、r the comparison have in totally sink decline is more and greatly, so changed the sex form of the P- s curve, can push to know if use the compression of the mat layer quantity to the compound the foundation P- s curve carries on the correction, it will recover the P- s of the single stake curve of a

47、bove, regrettable this engineering did not measure the compression quantity of the mat layer actually.3.2 The mat layer compresses the test of the quantity for the sake of the research the compression of the mat layer quantity to compound the influence of the foundation P- s curve, especially do the

48、 following experiment.For measuring the compound foundation actuallyMedium the compression quantity of the mat layer, adoption,such as figure,5 the device that show, at the steel carries the lotus plank up drill 8 s 12 of a bore,4 among them locate stake soil up,4 locate a top.Put the steel plastic

49、sheet center of the 100 mm × 100 mms, thick 5 mms aimed at the eyelet on the soil before the cushion layer and a crest, then spread the mat layer even, use the wood solid.Carry the lotus plank up of the center of a bore and the steel plastic sheet aim at, put up carry the lotus plank,10 steel p

50、oles of the long 25 cmses of on carrying to whet even, another on carrying to whet sharp form of it , insert the mat layer from a bore the steel pole, until and close contact of the steel plastic sheet.Adopt two sets of devices that prognosticate to transform, a set of prognosticate to carry the lot

51、us knothole to sink to decline through the basis beam, another appearance takes carrying the lotus plank as the basis to prognosticate the steel pole with carry the opposite of the lotus knothole move, this move the value is the mat layer of compression.Adopt the above device, apply compound in the

52、some engineering the foundation calm down carry the lotus experiment win carry on the test.The cement mixs blend a long 10 ms, a path 550 mms, the stake is apart from the 1.0 ms, presenting the isosceles triangle to arrange.Test the result,such as figure,6, figure 7, figure 8 show.Figure 7, figure 8

53、 won to list 1#,2# to try the curve of P- s and the curve of P- of the stake.( the measures for the compression of the mat layer)From the diagram it is thus clear that, the amount of compression of the mat layer is very big of, being the lotus to carry the p=700 kPas,1# mat on the stake layer compre

54、sses to measure for the 7.13 mms, the mat on the soil layer compresses to measure for the 4.89 mms;The mat layer compresses to measure for the 7.22 mms on 2# stake, the mat on the soil layer compresses to measure for the 5.17 mms.The amount of compression on the stake subtract the amount of compress

55、ion on the soil for a head stab into the quantity, can calculate, p=350 kPas,1# stake stab into the 1.55 mms,2# stake stab into the 1.74 mms;When p=700 kPas,1# stake stabs into the 2.20 mms,2# stake stabs into the 2.47 mms.It is thus clear that a head stabs into the quantity very obvious, but carry

56、to enlarge to refrain from rash action the trend with the lotus.Ascend the compression quantity that the average value of the compression of the mat layer regards as the mat layer with the compression quantity and soils of a mat layer, use to carry the lotus knothole to sink to decline the compressi

57、on quantity that the s subtracts the mat layer, carry on the correction to the curve of P- s, revise the curve of P- s of empress,such as figure,6 show.Revise in front and back two curves contrast and can see, the curve locates after revise above, sink to decline to diminish, and the curve shape too

58、k place the variety, curve of beginning start the segment straighter and even, sink to decline the acceleration along with the increment that lotus carry, with did not revise the ex- curve of P- s a beginning the creation sink to decline to become the fresh and clear contrast greatly more.When p=350 kPas,1# s=6.801 mms, =4.34 mms, s/ d=6.48%, / d=4.13%;2# s=6.523 mms, =4.03 mms, s/ d=6.21%, / d=3.84%, the compression of the mat layer transforms to have total 60% that sink to decline is above, the specific value that compresses to transform and carry the lotus plank diameter attains 4%, i