人民商場(chǎng)辦公樓基坑支護(hù)結(jié)構(gòu)設(shè)計(jì)畢業(yè)設(shè)計(jì)計(jì)算書(shū)

人民商場(chǎng)辦公樓基坑支護(hù)結(jié)構(gòu)設(shè)計(jì)畢業(yè)設(shè)計(jì)計(jì)算書(shū)人民商場(chǎng)辦公樓基坑支護(hù)結(jié)構(gòu)設(shè)計(jì)1設(shè)計(jì)方案綜合說(shuō)明1.1概述1.1.1工程概況擬建人民商場(chǎng)辦公樓采用框架結(jié)構(gòu),設(shè)兩層地下室,挖深為8m,局部挖深10m。位于解放路以西,迎賓路以北。本工程開(kāi)挖深度較大,但幾何形狀簡(jiǎn)單,且接近正方形。基坑周?chē)薪ㄖ锖凸艿赖仁姓迷O(shè)施。1.1.2基坑周邊環(huán)境條件基坑南面和東面均為馬路,最近距離為6m,下設(shè)通訊電纜、煤氣管線等設(shè)施。西側(cè)為居民住宅樓,其最近距離為分別為7m,北側(cè)為人民商場(chǎng),其最近距離為4m。1.1.3工程水文地質(zhì)條件擬建場(chǎng)區(qū)地貌單元為階地,地形較平坦。在基坑支護(hù)影響范圍內(nèi),自上而下有下列土層:1層素填土:灰黃~灰色,粉質(zhì)粘土為主,可塑~軟塑,混少量碎磚粒,爐渣,填齡大于10年。層厚0.5~1.0m。2層粉質(zhì)粘土:灰黃~灰色,可塑~軟塑,稍有光澤,無(wú)搖震反應(yīng),干強(qiáng)度中等,韌性中等。層厚1.1~2.0m。3-1層淤泥質(zhì)粉質(zhì)粘土:灰色,流塑,含腐植物,稍有光澤,無(wú)搖震反應(yīng),干強(qiáng)度低,韌性低。層厚1.5~2.0m。3-2層砂質(zhì)粉土:青灰~灰色,中密,砂顆粒成分以石英質(zhì)為主,含少量腐植物及云母碎片。層厚2.8~3.2m。3-3層淤泥質(zhì)粉質(zhì)粘土:灰色,流塑,含腐植物,夾薄層粉土,切面稍有光澤,韌性、干強(qiáng)度中等。層厚1.5~2.1m。4層淤泥質(zhì)粘土:灰色~灰黑色,軟~流塑,局部含泥炭及有機(jī)質(zhì),有腐臭味,稍有光澤,干強(qiáng)度中等,韌性中等。層厚1.1~2m。5-1層粘土:灰黃色~灰色,軟~可塑,切面有光澤,韌性、干強(qiáng)度較高。層厚1.1~3.0m。5-2層粉質(zhì)粘土:黃褐色,可塑~硬塑,稍有光澤,無(wú)搖震反應(yīng),干強(qiáng)度中等,韌性中等,含鐵錳結(jié)核及灰色高嶺土團(tuán)塊。層厚20m。場(chǎng)區(qū)有一層地下水,屬孔隙潛水類(lèi)型,地下水位深度在2.8m。主要接受降雨、地表水、地下徑流的補(bǔ)給。1.1.4基坑側(cè)壁安全等級(jí)及重要性系數(shù)人民商場(chǎng)辦公樓基坑要求支護(hù)結(jié)構(gòu)破壞、土體失穩(wěn)或過(guò)大變形對(duì)基坑周?chē)h(huán)境及地下結(jié)構(gòu)施工影響一般,所以取安全等級(jí)為二級(jí),基坑重要性系數(shù)γ01.0。1.2設(shè)計(jì)總說(shuō)明1.2.1設(shè)計(jì)依據(jù)(1)《人民商場(chǎng)辦公樓巖土工程勘察報(bào)告》K2013-59;(2)《建筑基坑支護(hù)技術(shù)規(guī)程》JGJ120-2012;(3)《混凝土結(jié)構(gòu)設(shè)計(jì)規(guī)范》GB50010-2002;(4)《鋼結(jié)構(gòu)設(shè)計(jì)規(guī)范》(GB50017-2003);(5)《建筑樁基礎(chǔ)技術(shù)規(guī)范》JGJ94-2008;(6)《巖土工程勘察規(guī)范》GB50021-2009。1.2.2支護(hù)結(jié)構(gòu)方案本工程基坑支護(hù)設(shè)計(jì)方案的設(shè)計(jì)計(jì)算,嚴(yán)格按照《建筑基坑支護(hù)設(shè)計(jì)規(guī)程》(JGJ120?2012)、《混凝土結(jié)構(gòu)設(shè)計(jì)規(guī)范》(GBJ50010?2002)、《鋼結(jié)構(gòu)設(shè)計(jì)規(guī)范》(GB50017-2003)中的有關(guān)要求進(jìn)行。同時(shí)采用了理正軟件進(jìn)行了輔助計(jì)算和驗(yàn)算;經(jīng)過(guò)詳細(xì)的計(jì)算分析后,我們認(rèn)為:采用本設(shè)計(jì)的基坑支護(hù)方案,能滿足基坑土方開(kāi)挖、地下室結(jié)構(gòu)施工及周?chē)h(huán)境保護(hù)對(duì)基坑支護(hù)結(jié)構(gòu)的要求,符合“安全可靠,經(jīng)濟(jì)合理,技術(shù)可行,方便施工”的原則。圖1-1基坑平面圖基坑分為ABC、CDE、EFA三個(gè)計(jì)算區(qū)段,如圖1-1所示,均采用鉆孔灌注樁與鋼筋混凝土支撐,基坑四周采用單排雙軸深攪樁止水結(jié)構(gòu)。本基坑工程的特點(diǎn)是基坑開(kāi)挖面積大,地基土層以淤泥質(zhì)土為主,基坑四周有主干道和建筑,且距離較小。周?chē)h(huán)境較復(fù)雜,必須確保周?chē)ㄖ铩⒌缆?、管線的正常安全使用,要求圍護(hù)結(jié)構(gòu)的穩(wěn)定性好、沉降位移小,并能有效地止水。因此,圍護(hù)結(jié)構(gòu)的設(shè)計(jì)應(yīng)滿足上述要求。綜合考察現(xiàn)場(chǎng)的周邊環(huán)境、道路及巖土組合等條件,為盡可能避免基坑開(kāi)挖對(duì)周?chē)ㄖ?、道路的影?經(jīng)過(guò)細(xì)致分析、計(jì)算和方案比較,本工程支護(hù)方案選用下列形式:整個(gè)基坑采用鉆孔灌注樁加一層鋼筋混凝土支撐作為支護(hù)結(jié)構(gòu)?；铀闹懿捎脝闻烹p軸深攪樁作止水結(jié)構(gòu)?；觾?nèi)采用集水坑排除地下水。1.3基坑監(jiān)測(cè)基坑監(jiān)測(cè)是指導(dǎo)正確施工、避免事故發(fā)生的必要措施,本設(shè)計(jì)制定了詳細(xì)的沉降、位移監(jiān)測(cè)方案:1沿壓頂梁布置觀測(cè)點(diǎn)、(2)在支護(hù)樁外側(cè)布置深層位移觀測(cè)孔、(3)沿周邊道路設(shè)沉降觀測(cè)點(diǎn)、(4)每幢建筑物上設(shè)一組沉降觀測(cè)點(diǎn)、(5)在支撐梁上布置應(yīng)力量測(cè)點(diǎn)。施工過(guò)程中將嚴(yán)格按照設(shè)計(jì)要求做好監(jiān)測(cè)、監(jiān)控工作。基坑開(kāi)挖施工前進(jìn)行一次觀測(cè),觀測(cè)值作為初始值,基坑開(kāi)挖前期每三天觀測(cè)一次,中期每?jī)商煊^測(cè)一次,開(kāi)挖至坑底后每天觀測(cè)一次,基坑或周?chē)h(huán)境位移變形較大時(shí),每天觀測(cè)兩次。基坑出現(xiàn)險(xiǎn)情時(shí),加密觀測(cè)。觀測(cè)成果應(yīng)及時(shí)反饋給業(yè)主、監(jiān)理、設(shè)計(jì)和施工單位。2基坑支護(hù)結(jié)構(gòu)設(shè)計(jì)計(jì)算書(shū)2.1設(shè)計(jì)計(jì)算2.1.1地質(zhì)計(jì)算參數(shù)根據(jù)本工程巖土工程勘察資料,各土層的設(shè)計(jì)計(jì)算參數(shù)如表2-1:表2-1土層設(shè)計(jì)計(jì)算參數(shù)層號(hào) 土層名稱(chēng) 層厚/m 重度γ(kN/m3) 內(nèi)摩擦角φo 粘聚力CkPa qskkPa 滲透系數(shù)10-6cm/s 10-6cm/s1 素填土 0.5~1.0 19.5 18.0 10.0 - - -2 粉質(zhì)粘土1 1.1~2.0 19 15.3 10 37 0.05 0.053-1 淤泥質(zhì)粉質(zhì)粘土1 1.50~2.0 16 14.0 15.0 29 1.45 4.953-2 砂質(zhì)粉土 2.80~3.2 21 19 7.0 41 14.5 45.53-3 淤泥質(zhì)粉質(zhì)粘土2 1.50~2.1 19 13.0 12 31 2.25 504 淤泥質(zhì)粘土 1.1~2 18 16.5 9.0 29 0.45 1.255-1 粘土 1.1~3 17.9 16.5 7.0 53 0 0.055-2 粉質(zhì)粘土2 20.00 17.1 9.0 8.0 45 0.15 2.52.1.2計(jì)算區(qū)段的劃分根據(jù)具體環(huán)境條件、地下結(jié)構(gòu)及土層分布厚度,將該基坑劃分為三個(gè)計(jì)算區(qū)段,其附加荷載及計(jì)算開(kāi)挖深度如表2-2:表2-2計(jì)算區(qū)段的劃分段位號(hào) ABC CDE EFA地面荷載(kPa) 20 20 20開(kāi)挖深度(m) 8 8 102.1.3計(jì)算方法按照《建筑基坑支護(hù)技術(shù)規(guī)程》(JGJ120-2012)的要求,土壓力計(jì)算采用朗肯土壓力理論,采用矩形分布模式,所有土層均使用水土合算。求支撐軸力時(shí)使用等值梁法,用力矩平衡求凈土壓力零點(diǎn)。樁長(zhǎng)是根據(jù)樁端力矩求出,并應(yīng)滿足抗隆起及整體穩(wěn)定性要求,各段的抗隆起、整體穩(wěn)定性驗(yàn)算、位移計(jì)算詳見(jiàn)電算結(jié)果。為了對(duì)比分析,除用解析法計(jì)算外,還用理正軟件電算。由于支護(hù)結(jié)構(gòu)內(nèi)力是隨工況變化的,設(shè)計(jì)時(shí)按最不利情況考慮。2.1.4土壓力系數(shù)計(jì)算按照朗肯土壓力計(jì)算理論作為土側(cè)向壓力設(shè)計(jì)的計(jì)算依據(jù),即:主動(dòng)土壓力系數(shù):Kaitg245°-i/2被動(dòng)土壓力系數(shù):Kpitg245°+i/2計(jì)算時(shí),不考慮支護(hù)樁體與土體的摩擦作用,且不對(duì)主、被動(dòng)土壓力系數(shù)進(jìn)行調(diào)整,僅作為安全儲(chǔ)備處理。計(jì)算所得土壓力系數(shù)表如表2-3所示:表2-3土壓力系數(shù)表土層 KaiKpi 1素填土 0.528 0.727 1.894 1.3762粉質(zhì)粘土 0.582 0.763 1.717 1.3103-1淤泥質(zhì)粉質(zhì)粘土 0.610 0.781 1.638 1.2803-2砂質(zhì)粘土 0.509 0.713 1.965 1.4023-3淤泥質(zhì)粉質(zhì)粘土 0.631 0.794 1.580 1.2574淤泥質(zhì)粘土 0.558 0.747 1.793 1.3395-1粘土 0.558 0.747 1.793 1.3395-2粉質(zhì)粘土 0.729 0.854 1.371 1.1712.2ABC段支護(hù)結(jié)構(gòu)設(shè)計(jì)計(jì)算該段為基坑?xùn)|~北側(cè)。建筑±0.00相當(dāng)于絕對(duì)標(biāo)高15.25m,整平后地面標(biāo)高為15.00m,支撐設(shè)在-1.5m處,樁頂標(biāo)高為-1.1m。實(shí)際挖深8.0m,結(jié)構(gòu)外側(cè)地面附加荷載q取20kPa,計(jì)算時(shí)以J1孔為例。2.2.1土層分布(如表2-4所示)表2-4ABC段土層分布層號(hào) 巖土名稱(chēng) 厚度(m)1 素填土 1.03-1 淤泥質(zhì)粉質(zhì)粘土 2.03-2 砂質(zhì)粉土 3.05-1 粘土 3.05-2 粉質(zhì)粘土 20.02.2.2土層側(cè)向土壓力計(jì)算2.2.2.1主動(dòng)土壓力計(jì)算Ea1120×0.528-2×10×0.727-3.98kPaEa1220+19.5×1.0×0.528-2×10×0.7276.316kPaEa2120+19.5×1.0×0.610-2×15×0.7810.665kPaEa2220+19.5×1.0+16×2×0.610-2×15×0.78120.185kPaEa3120+19.5×1+16×2×0.509-2×7×0.71326.411kPaEa3220+19.5×1+16×2+21×3×0.509-2×7×0.71358.479kPaEa4120+19.5×1+16×2+21×3×0.558-2×7×0.74764.593kPaEa4220+19.5×1+16×2+21×3+17.9×2×0.558-2×7×0.74784.569kPaEa51Ea52Ea4284.569kPaEa6120+19.5×1+16×2+21×3+17.9×2×0.558-2×8×0.854110.485kPaEa62Ea61110.485kPa2.2.2.2被動(dòng)土壓力計(jì)算Ep512×7×1.33918.746kPaEp5217.9×1×1.793+2×7×1.33950.841kPaEp6117.9×1×1.371+2×8×1.17143.277kPaEp6217.9×1+17.1×20×1.371+2×8×1.171512.519kPa2.2.2.3凈土壓力計(jì)算(坑地面以下)Ep5118.746-84.569-65.823kPaEp5250.841-84.569-33.728kPaEp6143.277-110.485-67.208kPaEp62512.159-110.485401.674kPa圖2-1ABC段土壓力分布圖2.2.3土壓力合力及作用點(diǎn)的計(jì)算LD13.98×1/3.98+6.3160.387mEa16.316×1-0.387/21.936KN/mHa11-0.387/30.204mEa20.665+20.185×2/220.85KN/mHa22/3×0.665×2+20.185/0.665+20.1850.688mEa326.411+58.479×3/2127.335KN/mHa33/3×26.411×2+58.479/26.411+58.4791.311mEa464.593+84.569×2/2149.162KN/mHa42/3×64.593×2+84.569/64.593+84.5690.955mEa533.728+65.823×1/249.776KN/mHa51-1/3×33.728×2+65.823/33.728+65.8230.107mLD667.208×20/67.208+401.6742.867mEa667.208×2.867/396.343KN/mHa62.867-2.867/31.911mEp620-2.867×401.674/23440.940KN/mHp620-2.867/35.711mEa1.936+20.85+127.335+149.162+49.776+96.343445.402KN/mMa1.936×11.071+20.85×9.555+127.335×7.178+149.162×4.822+49.776×2.974+96.343×1.9112186.068KN?m2.2.4支撐軸力計(jì)算經(jīng)計(jì)算:∑MaD2186.068KN?m∑Ea445.402KN/m支撐軸線位于地面下1.5m處由∑MD0得:R2186.068/(8+3.867-1.5)210.868kN/m反彎點(diǎn)反力P0計(jì)算:P0445.402-210.868234.534kN/m2.2.5樁長(zhǎng)計(jì)算設(shè)樁端進(jìn)入彎矩零點(diǎn)以下x米處,由∑M0得:1.2[2186.068+445.402x]210.86811.867+x-1.5+1/2×401.674×x/17.133×x×x/3解之得:x9.7m樁長(zhǎng)H9+2.867+9.721.567m,取22m,經(jīng)電算驗(yàn)算,滿足要求。2.2.6嵌固穩(wěn)定性驗(yàn)算根據(jù)《建筑基坑支護(hù)技術(shù)規(guī)程》JGJ120-2012中第4.2.2條由得:(3440.94×17.178)/(445.402×6.76)191.2滿足要求。2.2.7最大彎矩計(jì)算2.2.7.1R-P0間最大彎矩,M1計(jì)算:設(shè)剪力Q0點(diǎn)位于第3-2層底面以下x米處:210.8681.936+20.85+127.335+64.593x+1/284.569-64.593/2×x2解得:x0.88mM1210.868×6+0.88-1.5-1.936×5.204+0.88-20.85×3.688+0.88-127.335×(1.311+0.88)-64.593×0.88×0.88/2-0.5×84.569-64.593×0.88/2×0.882/3725.23KN?m2.2.7.2P0以下最大彎矩,M2計(jì)算:設(shè)剪力Q0點(diǎn)位于彎矩零點(diǎn)以下x米處:234.5341/2×401.674x/17.133x解得:x4.47mM2234.534×4.47-1/2×4.47×401.674×4.47/17.133×4.47/3699.38KN?m2.2.8拆撐計(jì)算本工程擬建兩層地下室,混凝土墊層200mm,地下室負(fù)2層底板厚800mm,負(fù)1層底板中心線位于地面下3.75m處,厚400mm,負(fù)1層頂板中心線位于建筑±0.00處,厚500mm。負(fù)1層底板換撐時(shí),支護(hù)樁懸臂位于位于地面下3.55m處。M1.936×(2.204+0.55)+20.85×(0.688+0.55)+26.411×0.55×0.55/2+(58.479-26.411)×0.55/3×0.55/2×0.55/335.43KN?m/m2.2.9配筋計(jì)算按《混凝土結(jié)構(gòu)設(shè)計(jì)規(guī)范》GB50010-2002第4.1.11條取樁徑Φ1000,樁心距1100,M725.23kNM,取砼強(qiáng)度C30,fc14.3N/mm2,主筋1820鋼筋(HRB335,均勻布置,fy300N/mm2,保護(hù)層厚度50mm,Φ8@200螺旋筋,Φ20@2000加強(qiáng)筋。As183145652mm2b3005652/14.33.1450020.1511+0.750.151-[1+0.750.1512-0.5-0.6250.151]1/20.31t1.25-20.63[M]2/314.3500sin3+3004505652sin+sin/1098.05kNm1.251.01.1M997滿足要求!配筋率As/A5652/50027.9‰min4‰,滿足設(shè)計(jì)要求!2.3CDE段支護(hù)結(jié)構(gòu)設(shè)計(jì)計(jì)算該段為基坑?xùn)|~南側(cè),建筑±0.00相當(dāng)于絕對(duì)標(biāo)高15.25m,整平后地面標(biāo)高為15.00m,支撐設(shè)在-1.5m處,樁頂標(biāo)高為-1.1m。實(shí)際挖深8.0m,結(jié)構(gòu)外側(cè)地面附加荷載q取20kPa,計(jì)算時(shí)以J11孔為例。2.3.1土層分布(如表2-5所示)表2-5CDE段土層分布層號(hào) 巖土名稱(chēng) 厚度(m)1 素填土 1.02 粉質(zhì)粘土 2.03-2 砂質(zhì)粉土 3.03-3 淤泥質(zhì)粘土 25-2 粉質(zhì)粘土 202.3.2土層側(cè)向土壓力計(jì)算2.3.2.1主動(dòng)土壓力計(jì)算Ea1120×0.528-2×10×0.727-3.98kPaEa1220+19.5×1×0.528-2×10×0.7276.316kPaEa2120+19.5×1×0.582-2×10×0.7637.729kPaEa2220+19.5×1+19×2×0.582-2×10×0.76329.845kPaEa3120+19.5×1+19×2×0.509-2×7×0.71329.466kPaEa3220+19.5×1+19×2+21×3×0.509-2×7×0.71361.953kPaEa4120+19.5×1+19×2+21×3×0.558-2×9×0.74764.953kPaEa4220+19.5×1+19×2+21×3+18×2×0.558-2×9×0.74784.48kPaEa5120+19.5×1+19×2+21×3+18×2×0.729-2×8×0.854114.276kPaEa52Ea51114.276kPa2.3.2.2被動(dòng)土壓力計(jì)算Ep512×8×1.17118.736kPaEp5217.1×20×1.371+2×8×1.171487.618kPa2.3.2.3凈土壓力計(jì)算(坑地面以下)Ep5118.736-114.276-95.54kPaEp52487.618-114.276373.342kPa圖2-2CDE段土壓力分布圖2.3.3土壓力合力及作用點(diǎn)的計(jì)算LD13.98×1/3.98+6.3160.387mEa16.316×1-0.387/21.936KN/mHa11-0.387/30.204mEa27.729+29.845×2/237.574KN/mHa22/3×7.729×2+29.845/7.729+29.8450.804mEa329.466+61.533×3/2136.4985KN/mHa33/3×29.466×2+61.533/29.466+61.5331.3238mEa464.953+84.483×2/2149.436KN/mHa42/3×64.953×2+84.483/64.953+84.4830.9564mLD595.54×20/95.54+373.3424.075mEa595.54×4.075/2194.66275KN/mHa54.075-4.075/32.717mEp6373.342×20-4.075/22972.736KN/mHa620-4.075/35.308mEa1.936+37.574+136.4985+149.436+194.66275520.107KN/mMa1.936×11.075+0.204+37.574×4.075+5.804+136.4985×6.075+1.3238+149.436×4.075+0.9564+194.66275×2.7172683.73KN?m2.3.4支撐軸力計(jì)算經(jīng)計(jì)算:∑MaD2683.73KN?m/m∑Ea520.107KN/m支撐軸線位于地面下1.5m處由∑MD0得:R2683.73/8+4.075-1.5253.78kN/m反彎點(diǎn)反力P0計(jì)算:P0520.107-253.78266.327kN/m2.3.5樁長(zhǎng)計(jì)算設(shè)樁端進(jìn)入彎矩零點(diǎn)以下x米處,由∑M0得:1.2[2683.73+520.107x]253.78×8+4.075-1.5+x+1/2[373.342×x/15.925]×x×x/3解之得:x10.39m樁長(zhǎng)H8+4.075+10.3922.465m,取22.5m,經(jīng)電算后,滿足要求。2.3.6嵌固穩(wěn)定性驗(yàn)算根據(jù)《建筑基坑支護(hù)技術(shù)規(guī)程》JGJ120-2012中第4.2.2條由得:(2972.736×16.983)/(520.107×7.02)131.2滿足要求。2.3.7最大彎矩計(jì)算2.3.7.1R-P0間最大彎矩,M1計(jì)算:設(shè)剪力Q0點(diǎn)位于第3-3層頂面以下x米處:253.781.936+37.574+136.4985+64.953x+1/284.483-64.953/2×x2整理得:4.8825x2+64.953x-77.75150解得:x1.1mM1253.78×7.1-1.5-1.936×5.204+1.1-27.574×3.804+1.1-136.4985×1.3238+1.1-64.953×1.1×1.1/2-0.5×84.483-64.953×1.1/2×1.12/3853.48KN?m2.3.7.2P0以下最大彎矩,M2計(jì)算:設(shè)剪力Q0點(diǎn)位于彎矩零點(diǎn)以下x米處:266.3271/2×[373.342x/15.925]x解得:x4.76mM2266.327×4.76-1/2×4.76×373.342×4.76/15.925×4.76/3846.36KN?m2.3.8拆撐計(jì)算本工程擬建兩層地下室,混凝土墊層200mm,地下室負(fù)2層底板厚800mm,負(fù)1層底板中心線位于地面下3.75m處,厚400mm,負(fù)1層頂板中心線位于建筑±0.00處,厚500mm。負(fù)1層底板換撐時(shí),支護(hù)樁懸臂位于位于地面下3.55m處。M1.936×(2.204+0.55)+37.574×(0.804+0.55)+29.466×0.55×0.55/2+1/2×0.55(61.533-29.466)×0.55/3×0.55/360.96KN?m2.3.9配筋計(jì)算按《混凝土結(jié)構(gòu)設(shè)計(jì)規(guī)范》GB50010-2002第4.1.11條取樁徑Φ1000,樁心距1100,M853.48kNM,取砼強(qiáng)度C30,fc14.3N/mm2,主筋2022鋼筋(HRB335,均勻布置,fy300N/mm2,保護(hù)層厚度50mm,Φ8@200螺旋筋,Φ20@2000加強(qiáng)筋。As20380.17602.65mm2b3007602.65/14.33.1450020.2031+0.750.203-[1+0.750.2032-0.5-0.6250.203]1/20.315t1.25-20.62[M]2/314.3500sin3+3004507602.65sin+sin/1272.58kNm1.251.01.1M1173.535滿足要求!配筋率As/A7602.65/50029.6‰min4‰,滿足設(shè)計(jì)要求!2.4EFA段支護(hù)結(jié)構(gòu)設(shè)計(jì)計(jì)算該段為基坑西~南側(cè),建筑±0.00相當(dāng)于絕對(duì)標(biāo)高15.25m,整平后地面標(biāo)高為15.00m,支撐設(shè)在-1.5m處,樁頂標(biāo)高為-1.1m。實(shí)際挖深10.0m,結(jié)構(gòu)外側(cè)地面附加荷載q取20kpa,計(jì)算時(shí)以J29孔為例。2.4.1土層分布(如表2-6所示)表2-6EFA段土層分布層號(hào) 巖土名稱(chēng) 厚度(m)1 素填土 1.03-2 砂質(zhì)粉土 3.03-3 淤泥質(zhì)粉質(zhì)粘土 2.05-1 粘土 3.05-2 粉質(zhì)粘土 20.02.4.2土層側(cè)向土壓力計(jì)算2.4.2.1主動(dòng)土壓力計(jì)算Ea1120×0.528-2×10×0.727-3.98kPaEa1220+19.5×1×0.528-2×10×0.7276.316kPaEa2120+19.5×1×0.509-2×7×0.71310.124kPaEa2220+19.5×1+21×3×0.509-2×7×0.71342.191kPaEa3120+19.5×1+21×3×0.631-2×12×0.79445.622kPaEa3220+19.5×1+21×3+19×2×0.631-2×12×0.79469.6kPaEa4120+19.5×1+21×3+19×2×0.558-2×7×0.74767.941kPaEa4220+19.5×1+21×3+19×2+17.9×3×0.558-2×7×0.74797.906kPaEa5120+19.5×1+21×3+19×2+17.9×3×0.729-2×8×0.854127.908kPaEa5220+19.5×1+21×3+19×2+17.9×3+17.1×1×0.729-2×8×0.854140.374kPaEa61Ea62Ea52140.374kPa2.4.2.2被動(dòng)土壓力計(jì)算Ep612×8×1.17118.736kPaEp6217.1×19×1.371+2×8×1.171464.174kPa2.4.2.3凈土壓力計(jì)算(坑地面以下)Ep6118.736-140.374-121.638kPaEp62464.174-140.374323.8kPa圖2-3EFA段土壓力分布圖2.4.3土壓力合力及作用點(diǎn)的計(jì)算LD13.98×1/3.98+6.3160.387mEa16.316×1-0.387/21.936KN/mHa11-0.387/30.204mEa210.124+42.191×3/278.4725KN/mHa23/3×10.124×2+42.191/10.124+42.1911.1935mEa345.622+69.6×2/2115.222KN/mHa32/3×45.622×2+69.6/45.622+69.60.9306mEa467.941+97.906×3/2248.7705KN/mHa43/3×67.941×2+97.906/67.941+97.9061.41mEa5127.908+140.374×1/2134.141KN/mHa51/3×127.908×2+140.374/127.908+140.3740.492mLD6121.638×19/121.638+323.85.188mEa6121.638×5.188/2315.53KN/mHa65.188-5.188/33.459mEp6323.8×19-5.188/22236.1628KN/mHp619-5.188/34.604mEa1.936+78.4725+115.222+248.7705+134.141+315.53894.072KN/mMa1.936×9.204+5.188+78.4725×1.1935+6+5.188+115.222×4.9306+5.188+248.7705×2.41+5.188+134.141×0.492+5.188+315.53×3.4595906.92KN?m/m2.4.4支撐軸力計(jì)算經(jīng)計(jì)算:∑MaD5906.92KN?m/m∑Ea894.072KN/m支撐軸線位于地面下1.5m處由∑MD0得:R5906.92/10+5.188-1.5431.54kN/m反彎點(diǎn)反力P0計(jì)算:P0894.072-431.54462.532kN/m2.4.5樁長(zhǎng)計(jì)算設(shè)樁端進(jìn)入彎矩零點(diǎn)以下x米處,由∑M0得:1.2[5906.92+894.072x]431.5415.188+x-1.5+1/2[323.8×x/13.812]×x×x/3解之得:x13.6m樁長(zhǎng)H10+3.459+13.627.059m,實(shí)取27m,經(jīng)電算驗(yàn)算,滿足要求。2.4.6嵌固穩(wěn)定性驗(yàn)算根據(jù)《建筑基坑支護(hù)技術(shù)規(guī)程》JGJ120-2012中第4.2.2條由得:(2236.1628×19.392)/(894.072×8.8)5.51.2滿足要求。2.4.7最大彎矩計(jì)算2.4.7.1R-P0間最大彎矩,M1計(jì)算設(shè)剪力Q0點(diǎn)位于第5-1層頂面以下x米處:431.541.936+78.4725+115.222+67.941x+1/297.906-67.941/3×x2解得:x2.86mM1431.54×8.86-1.5-1.936×5.204+2.86-78.4725×3.1935+2.86-115.222×0.9306+2.86-67.941×2.862/2-0.5×97.906-67.941×2.86/3×3.822/31931.92KN?m2.4.7.2P0以下最大彎矩,M2計(jì)算設(shè)剪力Q0點(diǎn)位于彎矩零點(diǎn)以下x米處:462.5321/2×323.8x/13.812×x/2解得:x6.28mM2462.532×6.28-1/2×6.28×323.8×6.28/13.812×6.28/31937KN?m2.4.8拆撐計(jì)算本工程擬建兩層地下室,混凝土墊層200mm,地下室負(fù)2層底板厚800mm,負(fù)1層底板中心線位于地面下3.75m處,厚400mm,負(fù)1層頂板中心線位于建筑±0.00處,厚500mm。負(fù)1層底板換撐時(shí),支護(hù)樁懸臂位于位于地面下3.55m處。M1.9362.754+10.1242.552/2+1/242.191-10.1242.553/967.787KN?m2.4.9配筋計(jì)算按《混凝土結(jié)構(gòu)設(shè)計(jì)規(guī)范》GB50010-2002第4.1.11:取樁徑φ1000,樁心距1100,M1937(kNM),取砼強(qiáng)度C30,fc14.3N/mm2,主筋2040鋼筋,,均勻布置,fy300N/mm2,保護(hù)層厚度50mm,Φ8@200螺旋筋,Φ20@2000加強(qiáng)筋。As201256.625132mm2b30025132/14.33.1450020.6711+0.750.671-[1+0.750.6712-0.5-0.6250.671]1/20.345t1.25-20.56[M]2/314.3500sin3+30045025132sin+sin/2836kNm1.251.01.1M2663滿足要求!配筋率As/A25132/500231‰min4‰,滿足設(shè)計(jì)要求!2.5支撐結(jié)構(gòu)設(shè)計(jì)計(jì)算內(nèi)支撐結(jié)構(gòu)采用鋼筋混凝土支撐,取支撐力R431.54KN/m,支撐對(duì)撐間距取為8m,角撐間距取為7m,立柱樁間距取10m。支撐梁截面為500×700,混凝土等級(jí)為C30。2.5.1支撐軸力N角1.25×431.54×7/cos45o7187.92KNN對(duì)1.25×431.54×84315.4KN取N7187.92KN2.5.2支撐彎矩計(jì)算2.5.2.1支撐梁自重產(chǎn)生的彎矩q1.25×0.5×0.7×2510.94KN/mM11/10×10.94×102109.4KN?m2.5.2.2支撐梁上施工荷載產(chǎn)生的彎矩取q10.0KN/mM21/10×10×102100KN.m2.5.2.3支撐安裝偏心產(chǎn)生的彎矩M3N×e7187.92×10×3‰215.6KN?m則支撐彎矩為:M109.4+100+215.6425KN?m2.5.3初始偏心距eie0M/N425×103/7187.9259.1mm根據(jù)《混凝土結(jié)構(gòu)設(shè)計(jì)規(guī)范》GB50010-2002中7.3.3可知:eah/30700/3023.320mm則eie0+ea59.1+23.382.4mm2.5.4是否考慮偏心矩增大系數(shù)η∵l0/h10/0.714.35.0∴要考慮由ξ10.5×14.3×0.5×0.7×103/7187.920.3481.0取ξ10.348∵l0/h10/0.714.315∴取ξ211.409×82.4116.1mm2.5.5配筋計(jì)算∵116.1mm0.3199.5mm且N7187.92KNNb2615.1,屬于小偏心受壓∴為小偏心受壓e+-a116.1+350-35431.1mm[7187.92×431.1×103-1.0×14.3×500×700×(665-350]/[360×665-35]6712?2(7187.92×103-1.0×14.3×500×700-360×6712)/3600由于N7198.9214.3×500×7005005kN所以還應(yīng)驗(yàn)算反向破壞。7187.92×103×[0.5×700-35-(59.1-23.3]-1.0×14.3×500×700×665-350/[360×665-35]1897.230為了防止鋼筋的一側(cè)壓壞,初步配筋為As選用1032,As8042mm2,選用1032,8042mm2As700mm2由求x7187.92×103×431.11.0×14.3×500x665-x/2+360×8042×665-35X372.40.55×665365.75實(shí)配:上下均為1032,AsAs’8042mm2配筋率As/A8042/500×70022.9‰min4‰,滿足設(shè)計(jì)要求!2.5.6整體穩(wěn)定性驗(yàn)算穩(wěn)定性系數(shù):l0/b10/0.520查表:0.750.9×0.75[14.3×500×700+360×8042×2]7286.787kNN7187.92所以安全,可按構(gòu)造配筋2.5.7聯(lián)系梁截面尺寸400×500,取砼C30,取最小配筋率為min3‰,則最小配筋面積為Amin3‰×400×500600mm2,上下均配4Φ18,A1017Amin,Φ8@200四肢箍。2.6圈梁設(shè)計(jì)計(jì)算本設(shè)計(jì)共分為三個(gè)段面,混凝土支撐直接作用于圈梁上,由于三個(gè)段面的作用力相差較大,分別為211KN,254KN,432KN,故圈梁設(shè)計(jì)分三段進(jìn)行,設(shè)計(jì)圈梁均為800×1100,C30砼。2.6.1ABC段圈梁設(shè)計(jì)計(jì)算2.6.1.1正截面強(qiáng)度計(jì)算211×72×1.251292.375KN?mαs1292.375106/14.3800106520.1γs0.51+0.95As1292.375106/0.9530010654258實(shí)取2×525,有As4908As4908mm2ρminA0.00380011002640mm2滿足最小配筋率要求。2.6.1.2斜截面強(qiáng)度計(jì)算V1/221171.25923.125KN0.70.71.438001065852.9KNV需配箍筋:取Φ8@200四肢箍0.7+1.250.7×1.43×800×1065+1.25×210/1000×4×4×4×3.14/200×10651134.1KNV917N滿足要求。2.6.2CDE段圈梁設(shè)計(jì)計(jì)算2.6.2.1正截面強(qiáng)度計(jì)算254×97×1.251555.75KN?mαs1555.75106/14.3800106520.12γs0.51+0.94As1555.75106/0.9430010655180故實(shí)取2625有As5890。AsρminA0.00380011002640mm2滿足最小配筋率要求。2.6.2.2斜截面強(qiáng)度計(jì)算V1/225471.251111.25KN0.70.71.438001065852.9KNV需配箍筋取Φ8@200,四肢箍0.7+1.251134.1kNV滿足要求。2.6.3EFA段圈梁設(shè)計(jì)計(jì)算2.6.3.1正截面強(qiáng)度計(jì)算1/10432×72×1.252646KN?mαs2646106/14.3800106520.2γs0.51+0.89As2646106/0.8930010659305實(shí)取21025有As9817As9817mm2ρminA0.00380011002640mm2滿足最小配筋率要求。2.6.3.2斜截面強(qiáng)度計(jì)算V1/243271.252268KN0.70.71.438001065852.9KNV需配箍筋取12@100,四肢箍0.7+1.252660kNV滿足要求。2.7立柱強(qiáng)度計(jì)算2.7.1上段鋼立柱采用Φ32510鋼管a、立柱上所承受的豎向壓力P支撐、聯(lián)系梁、活載、自重P11.25×25×10×0.5×0.7+7×0.4×0.5×2+10×10+7+7436.875KNb、使支撐縱向穩(wěn)定所需的水平壓力產(chǎn)生的豎向荷載P20.14321.258432KN436.875+432868.875KNc、Φ32510鋼管特征系數(shù)及強(qiáng)度驗(yàn)算:A6010mm2W1.48106mm3i112.8L08m,λL0/i70.9查表得Φ0.745N/ΦA(chǔ)868.875103/0.7456010194[f]2052.7.2下段鋼筋砼立柱強(qiáng)度驗(yàn)算取立柱樁徑1000,基坑面下樁長(zhǎng)L米,取qs26KPaP868.875+3.140.52L25×1.2868.875+23.55LKNFDfL3.14126L81.64L由F1.2P得L19實(shí)取L19M配筋:主筋為14Φ20,螺旋筋Φ8@200,上部加密,加強(qiáng)筋Φ20@2000。314×14/3.14×50020.00560.002,滿足要求。2.8基坑止降水設(shè)計(jì)2.8.1止水樁長(zhǎng)確定坑外水位取地面下2.8m,坑內(nèi)水位取地面下12m。D8.36m止水樁長(zhǎng)為:h12+8.36-2.817.56m,取18m。2.8.2滲流穩(wěn)定性分析(10-9.2+2×17)×7.1/[(10-9.2)×10]2.0滿足要求。2.8.3基坑止水帷幕設(shè)計(jì)考慮目前普通深攪樁機(jī)的施工能力和本基坑的開(kāi)挖深度等情況,確定深攪樁有效樁長(zhǎng)為18m?；又顾∧徊捎靡慌纽?00@900的雙軸深攪樁,樁體搭接300mm。施工工藝