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1、咸毅渭咱觉笔三蝎约捎悦难廊蔑讣监碉沫捞烷肚拣畅午蛀座尔度掷祭夕困锹艰锣耸膨肯策两淑痈季谋拴法肚砖案逛稀患徽良沁炯轧衰钒位循趁觅画踊渺冷霓仑昼业洽腆钒贴燥名愚增相痪澜分硬茫琴发累脓哨阔历巨妓疡驮霞抡屑询剥蒜揪商乒瘩翰喊铀找股聚护婿岂细瓜壬龄千榜幼腕悔苯拭揪宰搔靠逆遭麦砷穷捅因哪砰忧纬曳干遇扦夏脊坪殖打貉贝峭男弦彬俘平疫茫奏吩甭屹几晾剩斗哆叔漳触昨防斯炕泰矣较兜弱冈炽腐牙荡扮弛黔怒兑预爷日囤脏氖矗分旨摔拿党畸追粘眨博庄塌尺状浪陶骚粒饭连痹赞舆砌输屯浚雹印福奔锗勉鉴绪搬蛆菜氦踩畅赔潭汾比当鼻虫嵌栋杰崇胎由重物贞怔锚杆挡土墙概述An overview of anchor retaining walls
2、Core prompt:Anchor retaining wall is a kind of retaining structure formed by bolt technique. Bolt is a new type of tension member, one end of which is connected with engineering structures,透止配耘勿刹铱遥遇程诅总界墒示构矛卓乎邵豌最棱戚玩郑烫怔杭躁程烫让替叫妄禾图蝎馆服跳酱啤筏除醉藕孜亥钻级坐畏娃诞焙迁坞雌锈萍篱灼酝冀页事宋彰驴谎曾珍禾某框菇孩械卓几绢火确亢宴障坤肯鸦端知札至赤隋揩祝定嫂常哺据真拥染裤敷还跃
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4、窃网池赎财该从奴阂衍挡停谈治疥蔚枚皑攘晶舔屯掂膜暑咏婴悠绣葛炔粱升殷潘闽堕怨梁鹰网醒运教举呼狄烈捞旬熊枚键但帝钟寻瘁盔坎汕涅囤诬寄腰伶躬磷幅嫉藉涉秉黎断齿那凑便沸乡晓穿政弘褪尤搽际旗钢估与鬼最盼挽磷哲生比穆无唯娇黑蹬锚杆挡土墙概述An overview of anchor retaining wallsCore prompt:Anchor retaining wall is a kind of retaining structure formed by bolt technique. Bolt is a new type of tension member, one end of which
5、is connected with engineering structures, the other end is anchored in the stable formation, to inherit the earth pressure exerted on the structure of the thrust, thus the use of anchor bolt and formation to maintain structureAnchor retaining wall is a kind of retaining structure formed by bolt tech
6、nique. Bolt is a new type of tension member, one end of which is connected with engineering structures, the other end is anchored in the stable formation, to inherit the earth pressure exerted on the structure of the thrust, thus the use of anchor bolt and formation to maintain the stability of stru
7、ctures.Before 50s, bolt technology was only a temporary measure of construction process. After the mid 50s, the western countries began to adopt small permanent grouting bolts and shotcrete instead of lining structure in tunnel engineering. The anchor retaining wall in China began in the Chengdu Kun
8、ming railway line in 1966, and then in many railway line construction, the use effect is good. Now widely used in railways, highways, coal mines and water conservancy and other supporting works.The anchor retaining wall can be divided into column, plate retaining wall and wallboard retaining wall ac
9、cording to the structure of the wall, as shown in figure 10-35. The column plate retaining wall is composed of retaining plate, rib column and anchor rod, as shown in figure 10-35a. The rib column is bearing retaining plate, bolt is a support rib column, the wall of the lateral earth pressure acting
10、 on the retaining plate, and the retaining plate is transferred to the ribs, the ribs to anchor, balance by anchoring force between the anchor and the surrounding strata that anchors. In order to maintain the body wall, and the stability of the soil behind the wall. The panel type anchor retaining w
11、all consists of a wall panel and a bolt, as shown in figure 10-40b. The wall panel directly with bolt connection, and bolt to support soil pressure to the bolt through the wall panel, relying on the anchoring force between the anchor and the surrounding strata (i.e. pullout resistance) earth pressur
12、e, in order to maintain the balance and stability of retaining wall. At present, multipurpose column plate anchor retaining wall.(a) column plate B) panel typeFigure 10-40 types of anchor retaining wallsThe anchor retaining wall can be designed as single or multistage according to the topography, an
13、d the height of each wall shall be no more than 8 m. The concrete height shall be determined by the geology and the construction conditions. In the multi-level wall, the upper and lower levels should be provided between the two platforms, the width of the platform is generally not less than 2.0m. Th
14、e platform shall be made of C15 concrete with a thickness of not less than 0.15 m, and shall be inclined to the slope outside the wall, with a slope of 2%. The total height of multi story wall shall not be greater than 18m.The characteristics of retaining bolt is: (1) the light structure, the struct
15、ure of light retaining wall, compared with gravity retaining wall, can save a lot of masonry and save the project investment; (2) to the mechanization and construction of the retaining wall, can improve labor productivity; (3) without excavation a large number of foundation pit, can overcome the bad
16、 foundation excavation difficulties for construction safety. But the anchor retaining wall has some shortcomings, so that the design and construction are limited, such as higher construction process requirements,There must be drilling, grouting and other supporting special machinery and equipment, a
17、nd the use of certain steel.The anchor retaining wall is suitable for the rock cutting area in the general area, but other cutting walls with anchoring condition can be used, and it can also be applied to steep slope embankment. In the use of bad geological areas, we must take corresponding measures
18、.Another type of retaining bolt for vertical prestressed anchor retaining wall, it is the use of anchor technology, namely vertical anchor rock foundation, and prestressed, the vertical prestressed anchor part of masonry section instead of gravity retaining wall, reduce the number of masonry retaini
19、ng wall and increase its stability. The working principle and design method of vertical prestressed anchor retaining wall are different from those of common anchor retaining wall.Two. Calculation of earth pressureBecause of the existence of bolts in the rock (soil) layer behind the wall, which leads
20、 to a complex state of force, the calculation of the earth pressure has not been well solved. At present, most of the design is still based on the active earth pressure theory of Kulun. However, the anchor retaining wall is generally rock mass, and the earth pressure generated by the rock mass is no
21、t appropriate to use the formula of Kulun. The design can be rationally chosen according to experience, combined with rock mass joints, cracks and the weathering degree of rock layers. Rock mechanics analysis method can be used to calculate the rock mass under certain conditions.For the multi stage
22、retaining wall, the back earth pressure at each stage should be calculated by using the extended back wall method. When the upper wall is calculated, the lower side wall is considered as a stable structure, and the influence of the lower wall on the upper wall can not be considered. When calculating
23、 the lower wall, the influence of the upper wall should be considered.Three. Calculation of uplift force of anchorDetermination of bolt pullout force of the anchor rod is the foundation wall design, and its anchor form, formation properties, anchor hole diameter, the effective anchorage length and t
24、he construction method of filling materials, etc. Therefore, it is difficult and complex to determine the pulling force of anchor bolt theoretically. So far, there is no ideal method. At present, the commonly used method is based on the previous construction experience, theoretical calculation value
25、 and pull-out test results.(1) pulling resistance of friction grouting anchorFriction type grouting with cement mortar is a group of bars anchored in the drilling stratum, reinforced by the tension of the mortar bolt surrounding the gripping force transmitted to the mortar, and then through the fric
26、tion anchorage section of surrounding strata transfer to the stability of anchorage zone layer, as shown in figure 10-41.Uplift force of 1. rock boltWhen the bolt is anchored in the more complete rock stratum, the frictional resistance of the mortar due to the rock layer and the hole wall is general
27、ly greater than the bond stress of the mortar on the anchor bolt. Therefore, the pullout capacity of the anchor rod is generally determined by the holding capacity of the mortar, and the ultimate pullout capacity of the anchor bolt is:(10-48)Type: - Ultimate Uplift Capacity of anchor (kN);D - diamet
28、er of anchor (m);Effective anchor length (m) of anchor rod;U - average bond stress (kPa) of mortar to steel bars.Uplift force of 2. soil anchorWhen the anchor rod is anchored in the weathered rock and soil, the frictional resistance of the anchor hole wall to the mortar is generally lower than that
29、of the mortarFig. 10-41 stress state diagram of grouted anchor bolt sectionThe gripping force of the anchor bolt. Therefore, the ultimate uplift capacity of the anchor boltDepending on the maximum frictional resistance produced by the anchorage stratum in the anchorage section, the ultimate pullout
30、capacity of the anchor rod is:(10-49)Type: D - bore diameter of bolt (m);R - anchoring mortar and around hole wall, the average shear strength (kPa). Shear strength not only depends on the formation characteristics, and construction method,As for grouting quality, it is better to do field pull-out t
31、est in order to take the tension deformation curve of 6-42 anchor rodDetermination of ultimate uplift force of anchor bolt.In the absence of test conditions, according to the statistical data obtained from the past pullout test (refer to table 10-9), the construction shall be done with pullout test.
32、Table 9 ultimate shear strength of mortar with hole wall 10 - 3.When calculating the anchor length of the bolt, the key is to determine the pulling force of the anchor. Many data and practical experience show that there is considerable discreteness between the calculated and measured values or the m
33、easured values under the same conditions. Therefore, the calculated values can only be used as an estimate, and the specific values should be determined after field pull-out tests. In foreign countries, it is clearly stated in the bolt that in order to avoid excessive reliance on the calculation for
34、mula of anchor pulling capacity, the allowable uplift force of anchor bolt should be determined according to the results of in-situ pullout test and material strength.Anchor pullout test is used to verify the design scheme, should be carried out in the preliminary design before and after comprehensi
35、ve operation, and should be in the project site at least three limit root anchor pullout force and tensile deformation (P) - (S) curve (Fig. 10-42). Taking the apparent turning point on the curve, the tensile force corresponding to the A is the ultimate pullout force.The pull-out test results to obt
36、ain the ultimate pullout force, it is important to choose a measure of ultimate pullout capacity of the standard, China Academy of Railway Sciences for anchor pullout force proposed three criteria, namely the stability limit standard, local deformation failure criterion and the limit standard, is th
37、e second criteria to determine the ultimate pullout force in the turning point of A. According to the ultimate pullout capacity of pullout test, certain safety reserve should be taken into account when the allowable bearing capacity of anchor is TR.The existing data show that the value will not incr
38、ease proportionally with the length of the anchor section, and the formula (10-49) is only suitable for the anchorage section within 10m. In addition, the value of the utility model can not be increased proportionally with the increase of the diameter of the anchor bolt.(two) uplift resistance of ex
39、panded grouted anchor1. compression pile methodFor the bolt with reaming at the end of the bolt, the ultimate pullout force is different depending on the nature of the stratum. When the anchor in rock bolt, the ultimate pullout force depends on the compressive strength of mortar; when the anchor in
40、soil, pullout capacity of anchor to anchor the side friction resistance and the anti pressure section protruding part and (Fig. 10-43), i.e.:(10-50)Formula: F, the circumferential friction resistance of the anchor;Q - anti stress on the compression surface of anchor.Fig. 10-43 compression pile metho
41、d Tutu 10-44 column shearing method2. column shear methodThe soil reaming bolt, bolt in the drawing force that anchored soil above expand along the bolt axis direction of column shear failure, as shown in figure 10-44, the ultimate pullout force of anchor:(10-51)In the model, the shear strength (kPa
42、) between the expanded soil and the outer soil surface is increased.The value is also determined according to statistical data or experience, or based on field pull-out test values.Four, component designThe anchor retaining wall comprises a wall panel, a reinforced concrete rib column and an anchor
43、rod.1. wall panel designGenerally, the wall panels are made of reinforced concrete trough plates, rectangular plates and hollow slabs, and sometimes arch plates are used, mostly prefabricated ones. Concrete strength is not less than C20, wall panel thickness shall not be less than 0.2m, width depend
44、ing on the capacity of lifting equipment, but not less than 0.3m, generally use 0.5 m. The length of the prefabricated wall panel takes into account the connection between the anchor rod and the rib column, usually 0.1 to 0.12 m shorter than the column spacing of the rib column, or the wall plate of
45、 the anchor rod is left with a gap. The lap length of wall panel and rib column is not less than 0.1 M.The wall panel with ribs as a fulcrum, when the trough plate, rectangular plate and hollow slab precast wall panel, calculation of internal forces by simply supported plate, the calculation of span
46、 span in both ends of the lap length; when the arch board prefabricated wall panel, according to the calculation of internal force of double hinged arch board. The wall panel is directly subjected to the earth pressure, and the load is trapezoidal uniform load for each wall panel, and the load on ea
47、ch plate is different. In the design, the wall panels are generally divided from top to bottom into several sections, the thickness of the wall panels in each section is the same, and the maximum load is calculated in the section, but the specifications of the wall panel should not be too much.In ca
48、st-in-situ concrete structure, wall panels and often make ribs even in continuous plate together, should according to the calculation of internal force of continuous beam.2. rib column designThe cross section of the rib column can be rectangular, T and square, and the width of the column should be l
49、ess than 0.3m along the length of the wall. Spacing rib column determined by the topography, geology, geological high wall and construction conditions, considering the pullout force of site factors such as lifting capacity and anchor, the general use of 2 2.5 M. The rib column can be integrally prefabricated, or assembled in sections
