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原文：
Hoist the basic design of several issues
Abstract: This paper hoist and load transfer between the concrete foundation for a more detailed analysis; compared with the norms on the basis of the determination of stability factor on the basis of the stability of the hoist recommendations Coefficient value; and sets out to improve the upgrade?Resistance Capability of machine base measures for design.
Key words: local pressure; shear keys; overturning; anti-slip; stability
Preface
Surface coal mine hoist room is an important part of the production system.?Tied with Derrick important structures for the upgrading of the system.?With the increase in coal production capacity, upgrading the previous single-mode can no longer meet the needs of modern production, the progressive development of multi-round, multi-rope lifting way.?Enhance the rope's pull also increased and role of tension based on the hoist is also growing.?The past, the basis of a single Shengti lift weight alone can meet the requirements to enhance the stability of machine.?Requirements may construct the foundation made of plain concrete foundation.?Mine is a large machine used in multi rope, then part of the foundation alone hoist weight falls far short of basic stability.?Need to broaden the basis of weight or other technical measures using other anchor.?Thereby enhancing machine-based design raises new problems and new demands, more and more attention by the engineering and technical personnel.
1 Hoist-based stress analysis
1.1Determination of hoist rope tension
Wire rope at one end and raise the container skip or cage connected to the other end is connected with the hoist drum.?Derrick and hoist through the support form the basis of force balance system.?Therefore, the wire rope in the rope load derrick load can indeed?.Determined as follows:?
1) The normal work load when the hoist rope (Qk) Standard value: press "Mine headframe design" GB50385 - 2006 No. 41113 in the calculation.?
2) when the wire rope off rope load (Ak) standard values for single-Sheng Ti l, in which a rope for the break Sheng He set out, the other 2 times the normal load; for multi rope, of which the sideSheng He set all the broken rope, the other side of the 0133 times for all the rope off Sheng He set.
1.2Hoist equipment and basic load transfer between
General equipment manufacturers to provide information to enhance machine-based, and structure associated with: Equipment and size point of the force, Hole, casing, bolts and steel shear keys and so on.?Figure 1.
Known by the Figure 1: hoist by bolts in tension, shear steel shear key to the level of force transmission to the foundation.?
Hoist the basis of the whole, for the massive foundation.?Computational model of a rigid body, based on relatively little between the various parts of deformation, stress level is low, generally may from time to calculate an overall strength.?70's Red Flag Factory in the 20th century brand compressor assembly-based determination of the surface of steel stress is only 70 ~ 140N / cm2 [1].?The large volume of concrete foundation construction concrete hydration heat in order to prevent the formation of internal and external temperature, and the temperature cracks, generally require basic structural steel surface configuration.?But in the elevator equipment and the direct interaction between the concrete foundation of some of the stress concentration significantly, the need for computing and reinforcement, the designer often easy to overlook.Mainly for the following two parts: the basis of concrete local office bolt pressure plate, steel embedded in concrete shear key part.?The two sites of force transmission to the base hoist the key parts of the design should enhance the machine-based reinforcement calculation of local stress and attention.?The following detailed discussion of these two parts separately.
1.2.1Partial pressure of concrete
General bolts provided by the manufacturer, asked the location of civil engineering profession in the corresponding buried steel casing, elevator bolt and pull through the nut on the local pressure of concrete delivered to the concrete foundation.?Concrete local force model similar to the anchor plate with end.?Concrete in the base 450 along the failure surface diffusion to form a cone.?In order to avoid brittle fracture, can be extended to form a larger cone bolt failure surface, or around the bolt to configure the reinforced concrete so that the bolt pull in whole or in part by the reinforced passed on.?At this point requested by the destruction of tensile reinforcement in the cone base plane and the lower part of the length of not less than the tensile reinforcement anchorage length.
?Nut washer in concrete in the local compressive stress is concentrated, in order to prevent local crushing of concrete, this should be part of the reinforced concrete configuration indirect binding, the specific calculation and construction requirements see the "design of concrete structures" GB50010 - 2002 related to the requirements of section?.
Manufacturers to provide the embedded steel casing and internal bolt gap between the relatively large, refer to the anchor prestressing anchorage ends the construction requirements, should set the basis for concrete and steel pipe welded steel plate embedded.?Steel plate size to no more than the reserved ends bolt hole width is appropriate.?Set of steel plate has the advantage of stress can be further spread and reduce the stress level of concrete around the casing.
3. American Petroleum Institute, Spec!fication/br Wire Rope. APISpec(fication 9A (Spec 9A), 23rd edn. Washington, DC,1984.
4. Djivre, M., Mine ShaJ~ Ropes: Ontario Destructit~e Wire Testin,q Program. Ontario Ministry of Labour, Sudbury, Ontario,16 January 1991, p. 5.
2 Calculated based on the stability of the hoist
Hoist by bolts and steel and concrete shear key base fused to work together.?Rope force upgrade process requirements under the direction of the horizontal angle is generally not less than 50 °.?Improve the level and the vertical component rope are relatively large, and roughly equal.?Enhance the pull rope on a diagonal basis of the stability of negative factors.?Therefore, the stability of the need for basic computing.?Stability calculation based also includes two aspects: the basis and foundation for overturning the anti-slip.
2.1Overturning the basis of calculation
2.1.1Overturning stability calculations determine the rotation axis
Hoist by bolts and steel and concrete shear key base fused to work together.?Rope force upgrade process requirements under the direction of the horizontal angle is generally not less than 50 °.?Improve the level and the vertical component rope are relatively large, and roughly equal.?Enhance the pull rope on a diagonal basis of the stability of negative factors.?Therefore, the stability of the need for basic computing.?Stability calculation based also includes two aspects: the basis and foundation for overturning the anti-slip.
2.2 Calculated based on anti-slip
There are two possibilities based on sliding, a surface-based substrate and the substrate to overcome the friction between soil and sliding along the substrate surface.?Another level of force to overcome the internal friction of soil to foundation and the bearing layer of soil with the sliding part.?The latter generally difficult to occur because the substrate to allow the general stress of a certain safety factor, which guarantees the basal soil will not produce localized plastic flow to achieve the ultimate balance.?Therefore, the only case before the anti-slide stability checking.?
??? In the slide there are two favorable factors in the calculation are not taken into account.?① room with a certain thickness of concrete made on the basis of rigid anti-slide floor effect, in fact, reasonably rigid floor structure has a good foundation to prevent sliding function; ② backfill around the solid basis of a role in stabilizing certain basic?effect.?Also based on the foundation soil before the passive earth pressure are generally not considered because of passive earth pressure often associated with the basis of full sliding occurs, and is now commonly used Coulomb theory to yield the value of passive earth pressure is too large.?Therefore, taken together, can reduce the safety factor against sliding, especially in the case of accidental loads.
? ??"Mine headframe design" GB50385 - 2006 provides that: derrick-based anti-slip stability factor of 112.?Also provides: the foundation and basis for, from time to broken rope, anti-dropping braking effect of seismic load effect and the combination of checking.?
??? Therefore, the basis for the elevator (squat-type shallow foundation) in the off Sheng He set stable under the action of anti-slip coefficient is more appropriate for the 111 ~ 112, projects can be economical.
3 Other issues needing attention
1) Sometimes, in order to increase the basis of weight, often the reducer, motor base and hoist base as a single entity.?At this point, there are center-based force together with the projection rope hoist position of greater eccentricity.?In the design basis should be adjusted to some of the ground below, so that the center of the two as close as possible.?Weight in order to fully meet the theoretical assumptions.?
2) As the elevator based on the design layout of the main structure by the surrounding layout and can not re-expand size.?Can be taken to increase the anti-slide, anchor and uplift piles.?To ensure that the foundation Sheng He set off under the stability.?
3) To improve the capacity of hoist-based sliding the option following structural measures: ① set rigid floor, foundation backfill around the filling layer compacting ram; ② for soil under the foundation underside; ③ increase Depth of Foundation;?④ headframe and hoist room based on the actual layout of the situation can be the basis derrick hoist base and set the connection between the components to form a force balance.
譯文：
提升機(jī)基礎(chǔ)設(shè)計(jì)的幾個(gè)問(wèn)題
摘 要: 文章對(duì)提升機(jī)與混凝土基礎(chǔ)間的傳力進(jìn)行了較詳細(xì)的分析; 比較了各規(guī)范對(duì)基礎(chǔ)穩(wěn)定系數(shù)的確定, 對(duì)提升機(jī)基礎(chǔ)的穩(wěn)定系數(shù)取值提出了建議值; 并列出了提高提升機(jī)基礎(chǔ)抗滑能力的一些措施, 可供設(shè)計(jì)參考。
關(guān)鍵詞: 局部承壓; 抗剪鍵; 抗傾覆; 抗滑移; 穩(wěn)定性
前言
提升機(jī)房是煤礦地面生產(chǎn)系統(tǒng)的重要組成部分。與井架并列為提升系統(tǒng)的重要建筑物。隨著煤礦生產(chǎn)能力的提高, 以往單一的提升方式已不能滿(mǎn)足現(xiàn)代企業(yè)生產(chǎn)的需要,逐步發(fā)展到多輪、多繩的提升方式。提升鋼繩的拉力也隨之增大, 作用在提升機(jī)基礎(chǔ)上的拉力也越來(lái)越大。以往單繩提升機(jī)僅靠基礎(chǔ)自重即可滿(mǎn)足提升機(jī)的穩(wěn)定要求?；A(chǔ)也可按構(gòu)造要求做成素混凝土基礎(chǔ)。現(xiàn)在大型礦井中采用的多繩提升機(jī), 則僅憑提升機(jī)部分的基礎(chǔ)自重遠(yuǎn)遠(yuǎn)滿(mǎn)足不了基礎(chǔ)穩(wěn)定的要求。需要擴(kuò)大基礎(chǔ)的配重或另采用其它錨固的技術(shù)措施。從而對(duì)提升機(jī)基礎(chǔ)的設(shè)計(jì)提出了新的問(wèn)題和新的要求, 也越來(lái)越受到工程技術(shù)人員的重視。
1提升機(jī)基礎(chǔ)的受力分析
1.1提升機(jī)鋼繩拉力的確定
提升機(jī)鋼繩一端與提升容器箕斗或罐籠相連, 另一端與提升機(jī)滾筒相連。通過(guò)支撐井架與提升機(jī)基礎(chǔ)形成力的平衡系統(tǒng)。因此, 提升機(jī)鋼繩荷載可按井架中鋼繩荷載確定, 具體如下:
1) 正常工作時(shí)提升機(jī)鋼繩荷載(Qk )標(biāo)準(zhǔn)值:按《礦山井架設(shè)計(jì)規(guī)范》GB50385 - 2006 中第41113條計(jì)算。
2) 斷繩時(shí)提升機(jī)鋼繩荷,對(duì)于單繩提升, 其中一根鋼繩上為斷繩荷載, 另一根為2倍正常工作荷載;對(duì)于多繩提升, 其中一側(cè)為所有鋼繩的斷繩荷載, 另一側(cè)為所有鋼繩的0133倍斷繩荷載。
1.2提升機(jī)設(shè)備與基礎(chǔ)間傳力
一般設(shè)備廠家提供提升機(jī)基礎(chǔ)的相關(guān)資料, 與結(jié)構(gòu)相關(guān)的有: 設(shè)備力的作用點(diǎn)及大小、預(yù)留洞、套管、螺栓及型鋼抗剪鍵等。如圖1。
由圖1知: 提升機(jī)是通過(guò)螺栓受拉, 型鋼抗剪鍵受剪將水平力傳遞到基礎(chǔ)上。
提升機(jī)基礎(chǔ)從整體上看, 為大塊式基礎(chǔ)。其計(jì)算模型為剛體, 基礎(chǔ)各部分之間基本沒(méi)有相對(duì)變形, 應(yīng)力水平低,一般可不進(jìn)行整體強(qiáng)度計(jì)算。20世紀(jì)70年代某廠紅旗牌壓縮機(jī)裝配式基礎(chǔ)表面鋼筋應(yīng)力測(cè)定僅為70～140N / cm2 [ 1 ]。對(duì)于體積大的混凝土基礎(chǔ)為了防止施工混凝土水化熱形成內(nèi)外溫差, 導(dǎo)致溫度裂縫, 一般要求基礎(chǔ)表面配置構(gòu)造鋼筋。但是在提升機(jī)設(shè)備與混凝土基礎(chǔ)間的直接作用力的部分, 應(yīng)力集中現(xiàn)象明顯, 需要進(jìn)行計(jì)算和配筋, 往往設(shè)計(jì)人員容易忽略。主要為以下兩個(gè)部位: 螺栓墊板處基礎(chǔ)混凝土局部壓、型鋼抗剪鍵埋入混凝土的部分。這兩個(gè)部位為提升機(jī)傳力給基礎(chǔ)的關(guān)鍵部位, 設(shè)計(jì)中應(yīng)對(duì)提升機(jī)基礎(chǔ)的局部應(yīng)力和配筋計(jì)算引起高度重視。以下分別對(duì)這兩部分詳細(xì)討論。
1.2.1混凝土局部承壓
一般螺栓由廠家提供, 要求土建專(zhuān)業(yè)在相應(yīng)的位置埋設(shè)鋼套管, 提升機(jī)的螺栓上的拉力是通過(guò)螺帽對(duì)混凝土的局部承壓傳遞到混凝土基礎(chǔ)上?；炷辆植康氖芰δＪ筋?lèi)似于帶端板的錨栓。在基礎(chǔ)混凝土中沿450擴(kuò)散形成一個(gè)錐形破壞面。為了避免發(fā)生脆性破壞, 可加長(zhǎng)螺栓以形成更大的錐形破壞面, 或者在螺栓周邊混凝土中配置受拉鋼筋, 使的螺栓的拉力全部或部分由受拉鋼筋傳遞下去。此時(shí)要求受拉鋼筋在錐形破壞面內(nèi)和下部基礎(chǔ)中的長(zhǎng)度都不小于鋼筋的抗拉錨固長(zhǎng)度。
螺帽墊圈下混凝土中的局部壓應(yīng)力非常集中, 為防止混凝土局部壓碎, 應(yīng)對(duì)此部分混凝土配置間接鋼筋加以約束, 具體計(jì)算及構(gòu)造要求參見(jiàn)《混凝土結(jié)構(gòu)設(shè)計(jì)規(guī)范》GB50010 - 2002中相關(guān)章節(jié)的要求。廠家提供的預(yù)埋鋼套管與內(nèi)部螺栓之間的空隙比較大,參考預(yù)應(yīng)力鋼筋的錨具端頭錨固的構(gòu)造要求, 宜在基礎(chǔ)混凝土中設(shè)置與鋼套管焊接的預(yù)埋鋼墊板。鋼墊板的尺寸以不大于螺栓端頭的預(yù)留洞的寬度為宜。設(shè)置鋼墊板的好處在于可將壓應(yīng)力進(jìn)一步擴(kuò)散, 降低套管周邊混凝土的應(yīng)力水平。
2提升機(jī)基礎(chǔ)的穩(wěn)定計(jì)算
提升機(jī)通過(guò)螺栓與型鋼抗剪鍵與混凝土基礎(chǔ)連成一體,共同工作。提升鋼繩作用力的方向按工藝要求一般為與水平線(xiàn)的夾角不小于50°。提升鋼繩的水平和豎向分力均比較大, 且大致相等。提升鋼繩的斜向上拉力成為基礎(chǔ)的穩(wěn)定不利因素。因此需要進(jìn)行基礎(chǔ)穩(wěn)定性的計(jì)算。基礎(chǔ)的穩(wěn)定性計(jì)算又包括兩方面: 基礎(chǔ)的抗傾覆和基礎(chǔ)的抗滑移。
2.1基礎(chǔ)抗傾覆計(jì)算
2.1.1抗傾覆計(jì)算中轉(zhuǎn)動(dòng)軸的確定
進(jìn)行基礎(chǔ)抗傾覆穩(wěn)定性驗(yàn)算, 旨在保證提升機(jī)基礎(chǔ)不致向一側(cè)傾倒(繞基底的某一軸轉(zhuǎn)動(dòng)) 。建在彈性地基上的基礎(chǔ), 由于最大受壓邊緣陷入土內(nèi), 此時(shí)基礎(chǔ)的轉(zhuǎn)動(dòng)軸將在受壓最外邊緣的內(nèi)側(cè)某一條線(xiàn)上?；淄劣? 基礎(chǔ)轉(zhuǎn)動(dòng)軸將愈接近基底中心, 基礎(chǔ)的抗傾覆的穩(wěn)定性就愈低。但在設(shè)計(jì)基礎(chǔ)時(shí), 均要求基底邊緣最大壓應(yīng)力小于112倍的基底土承載力, 因此基底土的塑性區(qū)的擴(kuò)展范圍有限。從工程設(shè)計(jì)方便考慮, 仍取基礎(chǔ)外邊緣為轉(zhuǎn)動(dòng)軸。
基礎(chǔ)四周土的固著作用, 對(duì)抗傾覆也有一定的作用,但因力臂小, 因此一般不考慮。相對(duì)而言, 基礎(chǔ)四周的土對(duì)抗滑穩(wěn)定的作用更大一些。目前較常用的庫(kù)倫原理導(dǎo)得的被動(dòng)土壓力計(jì)算值偏大, 另外基礎(chǔ)四周的回填土的質(zhì)量也不穩(wěn)定且提升機(jī)基礎(chǔ)屬于淺基礎(chǔ)。因此穩(wěn)定計(jì)算中, 被動(dòng)土壓力一般都不考慮。
2.2基礎(chǔ)抗滑移計(jì)算
基礎(chǔ)的滑動(dòng)有兩種可能, 一為基礎(chǔ)克服基底面與基底土之間的摩擦力而沿基底面滑動(dòng)。另一種為水平力克服土體內(nèi)部的摩擦力使基礎(chǔ)與持力層土體的一部分一起滑動(dòng)。后一種情況一般不易發(fā)生, 因?yàn)橐话慊椎娜菰S壓應(yīng)力已有一定的安全系數(shù), 這就保證了基底土不致產(chǎn)生局部的極限平衡而達(dá)到塑性流動(dòng)。因此, 只進(jìn)行前一種情況的抗滑動(dòng)穩(wěn)定驗(yàn)算。
在抗滑計(jì)算中有兩個(gè)有利因素未考慮進(jìn)去。①室內(nèi)用混凝土做的一定厚度剛性地坪對(duì)基礎(chǔ)的抗滑作用, 實(shí)際上構(gòu)造合理的剛性地坪具有良好的防止基礎(chǔ)滑動(dòng)的功能; ②基礎(chǔ)四周回填土的固著作用對(duì)基礎(chǔ)抗滑有一定的作用。另外基礎(chǔ)前土體對(duì)基礎(chǔ)的被動(dòng)土壓力作用一般也不考慮, 因?yàn)楸粍?dòng)土壓力的充分發(fā)揮經(jīng)常伴隨基礎(chǔ)的滑動(dòng)出現(xiàn), 而且目前常用的庫(kù)倫原理導(dǎo)得的被動(dòng)土壓力計(jì)算值偏大。因此綜合考慮, 可以將抗滑安全系數(shù)降低, 特別是在偶然荷載作用的情況下。
《礦山井架設(shè)計(jì)規(guī)范》GB50385 - 2006中規(guī)定: 井架基礎(chǔ)的抗滑移穩(wěn)定系數(shù)為112。同時(shí)又規(guī)定: 地基和基礎(chǔ), 可不進(jìn)行斷繩、防墜制動(dòng)荷載效應(yīng)及地震作用效應(yīng)組合的驗(yàn)算。
因此, 針對(duì)提升機(jī)基礎(chǔ)(矮胖型淺基礎(chǔ))在斷繩荷載作用下抗滑移穩(wěn)定系數(shù)取值為111～112較為合適, 工程上可做到經(jīng)濟(jì)合理。
3其它需要注意的問(wèn)題
1) 有時(shí)為了加大基礎(chǔ)的配重, 常將減速器、電動(dòng)機(jī)的基礎(chǔ)與提升機(jī)基礎(chǔ)連為一體。此時(shí), 存在基礎(chǔ)的合力中心與提升機(jī)鋼繩合力的投影位置有較大的偏心。在設(shè)計(jì)中應(yīng)調(diào)整基礎(chǔ)在地面以下的部分, 使二者的中心盡可能接近。以便配重充分發(fā)揮, 符合計(jì)算假定。
2) 設(shè)計(jì)中由于提升機(jī)基礎(chǔ)平面布置受周?chē)黧w結(jié)構(gòu)布置影響, 不能再擴(kuò)大尺寸。則可采取增加抗滑板, 錨桿及抗拔樁等。來(lái)保證基礎(chǔ)在斷繩荷載下的穩(wěn)定性。
3) 為了提高提升機(jī)基礎(chǔ)的抗滑能力, 可選擇下列構(gòu)造措施: ①設(shè)置剛性地坪, 基礎(chǔ)周?chē)幕靥钔练謱雍惶蠲軐?shí);②基礎(chǔ)底面下?lián)Q土; ③加大基礎(chǔ)埋置深度; ④根據(jù)實(shí)際井架與提升機(jī)房的布置情況, 可在提升機(jī)基礎(chǔ)與井架基礎(chǔ)間設(shè)置連接構(gòu)件, 形成力的平衡。