水利工程施工截流施工設(shè)計(jì)

大渡河截流設(shè)計(jì)日期：2017年2月19日目錄TOC\o"1-3"\h\u1基本資料32、截流的水力計(jì)算52.1計(jì)算步驟52.1.1計(jì)算下游水位52.1.2戧堤頂部高程的確定52.1.3戧堤高度、頂長(zhǎng)與頂寬52.2截流過(guò)程分析與水力計(jì)算72.3合龍?jiān)O(shè)計(jì)流量組成82.4圖解法93.流態(tài)判別133.1求水深133.2求斷面平均流速134截流過(guò)程的水力參數(shù)及拋投料的計(jì)算154.1計(jì)算截流過(guò)程水力參數(shù)154.2拋投料的計(jì)算164.2拋投料尺寸的計(jì)算164.3拋投量計(jì)算175小結(jié)181基本資料大渡河上某水電工程采用單戧立堵進(jìn)占，河床的剖面圖見(jiàn)圖1。戧堤處水位~流量關(guān)系見(jiàn)表1和圖2。戧堤端部邊坡系數(shù)n=1.2，截流戧堤兩側(cè)的邊坡為1:1.5。截流材料采用當(dāng)?shù)氐闹辛：谠贫L(zhǎng)花崗巖，容重為26kN/m3。該工程壩址處天然水位~流量關(guān)系見(jiàn)表1，施工導(dǎo)流采用左、右岸各布置一條導(dǎo)流隧洞導(dǎo)流，左、右導(dǎo)流隧洞聯(lián)合泄流的上游水位和泄流流量關(guān)系見(jiàn)表2和圖3。圖1河床剖面圖表1壩址處天然水位~流量關(guān)系流量（m3/s）2503174105001000水位（m）952.15952.71953.48954.00955.87951.5951.5952952.5953953.5954954.5955955.5956956.5020040060080010001200流量（m3/s）高程（m）圖2壩址處天然水位—流量關(guān)系曲線表2上游水位—導(dǎo)流隧洞泄流量關(guān)系泄流流量（m3//s）01503004108001400上游水位（m）953.00955.40957.03958.00960.66964.12952952954956958960962964966050010001500流量（m3/s)上游水位（m）圖3上游水位—導(dǎo)流隧洞泄流量關(guān)系曲線2、截流的水力計(jì)算截流設(shè)計(jì)是施工導(dǎo)流設(shè)計(jì)重要組成部分，目前我國(guó)水利水電工程截流多采用立堵截流，本次設(shè)計(jì)按立堵截流設(shè)計(jì)。其設(shè)計(jì)內(nèi)容分為：截流水力計(jì)算、截流水力分區(qū)和備料量設(shè)計(jì)。截流設(shè)計(jì)流量的確定，通常按頻率法確定，也即根據(jù)已選定的截流時(shí)段，采用該時(shí)段內(nèi)一定頻率的某種特征流量值作為設(shè)計(jì)流量。一般地，多采用截流時(shí)段10%～20％的月平均或者旬平均流量作為設(shè)計(jì)標(biāo)準(zhǔn)。截流的水力計(jì)算中龍口流速的確定一般采用圖解法，截流水力計(jì)算如下。2.1計(jì)算步驟2.1.1計(jì)算下游水位截流設(shè)計(jì)流量，計(jì)算時(shí)不考慮戧堤滲透流量和上游槽蓄流量。根據(jù)壩址處天然水位與流量關(guān)系曲線，由內(nèi)插法可知,2.1.2戧堤頂部高程的確定截流設(shè)計(jì)流量為，對(duì)上游水位~導(dǎo)流隧洞泄流量關(guān)系曲線使用內(nèi)插法，可得設(shè)計(jì)流量對(duì)應(yīng)水位高程為956.74m，故取戧基高程為957m。2.1.3戧堤高度、頂長(zhǎng)與頂寬截流戧堤處河床底部高程為951m，可求得戧堤的設(shè)計(jì)高度為7m。若取河谷兩側(cè)坡比為1:1，由河谷在高程957m處寬度為46.9m，可求得戧堤頂部長(zhǎng)為48.9m，計(jì)算時(shí)按約為49m進(jìn)行計(jì)算，戧堤寬度取20m。通過(guò)對(duì)表3進(jìn)行表上作業(yè)，可得分流流量與上游水位關(guān)系曲線與龍口泄水曲線如圖4和圖5所示。表3水位與下泄流量跟龍口流量的關(guān)系上游水位（m）設(shè)計(jì)流量(m3//s)下泄流量（m3//s）Qd龍口流量Qg9532730.00273.00953.527331.25241.7595427362.50210.50954.527393.75179.25955273125.00148.00955.4273150.00123.00955.5273159.20113.80956273205.2167.79956.5273251.2321.77956.74273273.000.00圖4上游水位與下泄流量關(guān)系曲線圖5上游水位—龍口流量關(guān)系曲線2.2截流過(guò)程分析與水力計(jì)算隨著戧堤進(jìn)占，河床斷面不斷束窄，上下游落差亦逐漸增大，其斷面及流態(tài)變化過(guò)程如下：1）梯形淹沒(méi)流2）梯形非淹沒(méi)流3）三角形淹沒(méi)流4）三角形非淹沒(méi)流梯形斷面與三角形斷面的分界點(diǎn)的確定：，即當(dāng)龍口寬度大于14m時(shí)為梯形斷面，當(dāng)龍口寬度小于14m時(shí)為三角形斷面。由龍口泄水能力計(jì)算按照寬頂堰公式計(jì)算：式中——流量系數(shù)當(dāng)，為淹沒(méi)流，當(dāng)，為非淹沒(méi)流，——龍口平均過(guò)水寬度梯形斷面：三角形斷面：——龍口上游水頭梯形斷面：三角形斷面：其中：——龍口上下游水位差——戧堤高度——戧堤端部邊坡系數(shù)，取——龍口上游水位——河道底板高程由連續(xù)方程可得龍口流速計(jì)算公式為：-淹沒(méi)流時(shí)：式中：——龍口底板以上的下游水深非淹沒(méi)流時(shí)：式中：——龍口斷面的臨界水深=2\*ROMANI即淹沒(méi)出流時(shí)：=1\*GB3①對(duì)于梯形斷面：=2\*GB3②對(duì)三角形斷面：。=2\*ROMANII非淹沒(méi)出流時(shí)：=1\*GB3①對(duì)于梯形斷面：=2\*GB3②對(duì)三角形斷面：；2.3合龍?jiān)O(shè)計(jì)流量組成一般情況下，截流設(shè)計(jì)流量Q0由四部分組成：式中，Q——龍口流量；Qd——分流量（分流建筑物中通過(guò)的流量）；Qs——戧堤滲透流量；Qac——上游河槽中的調(diào)蓄流量。由于不考慮戧堤滲透流量和上游槽蓄流量，則有：。聯(lián)立上述方程：即可得到龍口處水力參數(shù)變化規(guī)律。2.4圖解法分別取定龍口寬度為B=6.5m，11.5m，16.5m，21.5m，26.5m，31.5m，36.5m，41.5m，46.5m時(shí)不同上游水位下的龍口泄流量和隧洞分流量。由截流設(shè)計(jì)流量358m3/s，壩址處天然水位—流量關(guān)系曲線內(nèi)插得設(shè)計(jì)流量下的壩址處天然水位為952.34m，設(shè)計(jì)中截流設(shè)計(jì)流量為定值，故認(rèn)為下游水位不變。龍口泄流量計(jì)算結(jié)果見(jiàn)附錄（附表4到附表12）。表4B=46.5m流量落差計(jì)算表BZH0Z/H0mBQg46.501.340.000.00031.3080.000.51.840.270.38031.308131.3312.340.430.38531.572192.631.52.840.530.38531.972260.8223.340.600.38532.372336.812.53.840.650.38532.773420.3434.340.690.38533.173511.213.54.840.720.38533.573609.3245.340.750.38533.973714.55表5B=41.5m流量落差計(jì)算表BZH0Z/H0mBQg41.501.3400.00026.6080.000.51.840.270.38026.608111.6212.340.430.38526.608162.341.53.840.390.38527.808356.6623.340.600.38526.608276.832.53.840.650.38526.608341.2734.340.690.38526.608410.053.54.840.720.38526.608482.9145.340.750.38526.608559.65表6B=36.5m流量落差計(jì)算表BZH0Z/H0mBQg36.501.340.00021.310.000.51.840.270.3821.3189.3812.340.430.38521.57131.621.52.840.530.38521.97179.2423.340.600.38522.37232.772.54.840.520.38523.57427.8234.340.690.38523.17357.113.54.840.720.38523.57427.8245.340.750.38523.97504.22表7B=31.5m流量落差計(jì)算表BZH0Z/H0mBQg31.501.340.000.00016.310.000.51.840.270.38016.3168.4112.340.430.38516.57101.111.52.840.530.38516.97138.4623.340.600.38517.37180.752.53.840.650.38517.77227.9534.340.690.38518.17280.053.54.840.720.38518.57337.0845.340.750.38518.97399.05表8B=26.5m流量落差計(jì)算表BZH0Z/H0mBQg26.501.340.000.00011.310.000.51.840.270.38011.3147.4412.340.430.38511.5770.601.52.840.530.38511.9797.6723.340.600.38512.37128.732.53.840.650.38512.77163.8234.340.690.38513.17203.003.54.840.720.38513.57246.3345.340.750.38513.97293.89表9B=21.5m流量落差計(jì)算表BZH0Z/H0mBQg21.501.340.000.0006.310.000.51.840.270.3806.3126.4612.340.430.3856.5740.101.52.840.530.3856.9756.8823.340.600.3857.3776.702.53.840.650.3857.7799.6934.340.690.3858.17125.953.54.840.720.3858.57155.5945.340.750.3858.97188.72表10B=16.5m流量落差計(jì)算表BZH0Z/H0mBQg16.501.2150.000.0001.6080.0000.51.7150.290.3831.6086.11612.2150.450.3852.23312.5471.52.7150.550.3852.73720.87023.2150.620.3853.24131.8462.53.7150.670.3853.74545.70834.2150.710.3854.24962.6753.54.7150.740.3854.75382.94745.2150.770.3855.257106.717表11B=11.5m流量落差計(jì)算表BZH0Z/H0mBQg11.510.1327.5950.3850.1330.0111.50.6322.3750.3850.6370.54521.1321.7670.3851.1412.3412.51.6321.5320.3851.6455.84432.1321.4070.3852.14911.4003.52.6321.3300.3852.65319.30543.1321.2770.3853.15729.8224.53.6321.2390.3853.66143.188表12B=6.5m流量落差計(jì)算表BZH0Z/H0mBQg6.530.04862.0690.3850.0490.0013.50.5486.3830.3850.5530.38341.0483.8160.3851.0571.9344.51.5482.9060.3851.5615.126由計(jì)算結(jié)果繪制不同寬度時(shí)上游水位與龍口泄流量關(guān)系曲線和龍口泄流量與上游水位關(guān)系曲線，曲線交點(diǎn)即為龍口在各寬度時(shí)的上游水位和泄流量，如下：圖6:龍口流量與上游水位的關(guān)系從上圖可看出，當(dāng)戧堤寬度較大時(shí)，上游水位較低，龍口泄流量較大。隨著龍口寬度減小，上游水位逐漸增高，龍口泄流量逐漸減小。當(dāng)龍口寬度為0時(shí)，上游來(lái)流全部經(jīng)由導(dǎo)流隧洞泄流。根據(jù)圖表數(shù)據(jù)求出各交點(diǎn)，結(jié)果見(jiàn)下表：龍口寬度B龍口泄流量Qd上游水位H46.5233.5953.6341.5222.3953.8136.5204.8954.0931.5185.8954.426.5160.5954.821.5126.4955.3516.582.7955.8411.531956.46.54.13956.69表13不同龍口寬度下的上游水位和龍口泄流量由上表中可看出，當(dāng)龍口寬度為46.5m時(shí)，龍口泄流量小于設(shè)計(jì)流量，這是因?yàn)樵诮亓魉τ?jì)算中沒(méi)有考慮戧堤的滲流和上游河床的調(diào)蓄流量，實(shí)際情況應(yīng)當(dāng)是龍口寬度為0時(shí)導(dǎo)流隧洞泄流量小于設(shè)計(jì)流量358m3/s。3.流態(tài)判別3.1求水深由表13中計(jì)算結(jié)果，判斷不同寬度下水流流態(tài)及堰流類型，并求相應(yīng)龍口斷面水深。計(jì)算表及結(jié)果見(jiàn)下表：表14不同寬度下的流態(tài)及水深BZH0Z/H0液態(tài)斷面類型h46.51.292.630.49非淹沒(méi)流梯形1.75441.51.472.810.52非淹沒(méi)流梯形1.87436.51.753.090.57非淹沒(méi)流梯形2.06031.52.063.40.61非淹沒(méi)流梯形2.26726.52.463.80.65非淹沒(méi)流梯形2.53421.53.014.350.69非淹沒(méi)流梯形2.90116.53.54.720.74非淹沒(méi)流三角形3.96111.54.063.191.27非淹沒(méi)流三角形2.6816.54.351.403.11非淹沒(méi)流三角形1.1753.2求斷面平均流速導(dǎo)截流工程中確定材料用料及用量時(shí)首先要計(jì)算戧堤龍口處的斷面流速，龍口流速計(jì)算公式為：式中，為龍口計(jì)算斷面水深，根據(jù)設(shè)計(jì)截流方法、斷面類型、出流類型根據(jù)規(guī)范求得。為過(guò)水?dāng)嗝嫫骄鶎挾龋慈缦路椒ㄓ?jì)算。當(dāng)斷面為梯形時(shí)，，當(dāng)斷面為三角形是，，為戧堤高度（7m），為戧堤端部邊坡系數(shù)（取1.0）。（1）梯形斷面淹沒(méi)流，，由于進(jìn)占過(guò)程中，龍口底部高程不變，為常數(shù)。（2）梯形斷面非淹沒(méi)流，，按下式計(jì)算，式中，——戧堤端部邊坡系數(shù)；——計(jì)算斷面動(dòng)能修正系數(shù)，常取計(jì)算。按上式計(jì)算需要進(jìn)行試算。有時(shí)為了簡(jiǎn)化計(jì)算，常用矩形斷面臨界水深代替梯形斷面臨界水深，此時(shí)（3）三角形斷面淹沒(méi)流，（4）三角形斷面非淹沒(méi)流，表15戧堤各寬度下龍口流速龍口寬度B龍口泄流量hV46.5233.51.75431.8044.18741.5222.31.87426.9484.40336.5204.82.06022.1724.48331.5185.82.26717.4204.70526.5160.52.53412.7414.97221.5126.42.9018.1815.32716.582.73.9614.7534.39211.5312.6813.2183.5936.54.131.1751.4102.494由上表中數(shù)據(jù)可知，龍口合攏過(guò)程中龍口流速變化先增大后減小。最大流速約為5.327m/s。4截流過(guò)程的水力參數(shù)及拋投料的計(jì)算4.1計(jì)算截流過(guò)程水力參數(shù)根據(jù)表18中結(jié)果列表計(jì)算龍口流速、單寬流量變化過(guò)程如下表所示：表19截流過(guò)程水力參數(shù)計(jì)算表B上下游落差ZV46.51.294.18741.51.474.40336.51.754.48331.52.064.70526.52.464.97221.53.015.32716.53.54.39211.54.063.5936.54.352.494由表19中數(shù)據(jù)可繪制龍口諸水力參數(shù)變化規(guī)律如下圖：圖7龍口諸水力參數(shù)變化規(guī)律圖4.2拋投料的計(jì)算拋投料計(jì)算主要為拋投塊尺寸的計(jì)算以及拋投量的計(jì)算。4.2拋投料尺寸的計(jì)算拋投料尺寸計(jì)算采用伊茲巴公式，即式中，為水流流速，m/s；為綜合穩(wěn)定系數(shù)；0.9為重力加速度，m/s2；為石塊容重，kN/m3；為水容重，kN/m3；為石塊折算成球體的化引直徑，m。其中v為水流流速，m/s;K為綜合穩(wěn)定系數(shù)；其中混凝土四方體取0.68-0.72，混凝土立方體取0.76-0.80，塊石取0.9；g為重力加速度，取;為石塊的容重，取；為水的容重，??；D為石塊折算成球體的化引直徑，m。根據(jù)伊茲巴公式求得各流速下的拋投料尺寸如下表：表20各龍口寬度下拋投塊粒徑BV粒徑d46.54.1870.66841.54.4030.73936.54.4830.76631.54.7050.84326.54.9720.94221.55.3271.08116.54.3920.73511.5