无纺布土袋护坡及水平铺盖下均铺设300g/m2无纺布反滤

参考工程区(qu)为(wei)河(he)(he)堤(di)桩(zhuang)号K1+200河(he)(he)段上下游(you)约400m范(fan)围内，河(he)(he)道(dao)水(shui)流在(zai)流经弯道(dao)时，受离心作用(yong)影(ying)响，在(zai)凸岸(an)(an)产(chan)生淤长(zhang)，而对凹(ao)岸(an)(an)进(jin)行冲刷，凹(ao)岸(an)(an)岸(an)(an)坡被(bei)(bei)侵蚀垮塌，河(he)(he)岸(an)(an)线被(bei)(bei)逐步(bu)侵蚀退(tui)移(yi)20～30m，部分河(he)(he)堤(di)已(yi)被(bei)(bei)冲毁，已(yi)严重威胁到河(he)(he)堤(di)安(an)全。

分析总(zong)结(jie)工程(cheng)弯道水毁产(chan)生(sheng)的(de)原因，工程(cheng)采(cai)取沿弯道凹岸(an)重新修(xiu)建护(hu)岸(an)工程(cheng)作为弯道水毁的(de)直(zhi)接防(fang)护(hu)措施(shi)，并结(jie)合(he)丁坝作为间接防(fang)护(hu)防(fang)治措施(shi)，利用丁坝群

将弯道主流(liu)挑离损毁河(he)道凹(ao)岸，并且(qie)通过(guo)水流(liu)在丁坝(ba)坝(ba)后产生(sheng)的(de)回水淤积，对弯道水毁进(jin)行(xing)生(sheng)态修复(fu)。

为避免石(shi)材及砼类护(hu)(hu)岸受工程(cheng)区(qu)冻涨影响及水(shui)(shui)流(liu)渗透掏(tao)空影响，护(hu)(hu)岸型(xing)式采用(yong)“无(wu)纺布(bu)土(tu)(tu)工袋(dai)(dai)护(hu)(hu)坡”，岸坡迎水(shui)(shui)面采用(yong)无(wu)纺布(bu)土(tu)(tu)袋(dai)(dai)防护(hu)(hu)，防护(hu)(hu)边坡为阶(jie)梯状，边坡系数为1:2.0，迎水(shui)(shui)面坡前设无(wu)纺布(bu)土(tu)(tu)袋(dai)(dai)水(shui)(shui)平铺盖，水(shui)(shui)平铺盖埋入平均河床高程(cheng)以下；在无(wu)纺布(bu)土(tu)(tu)袋(dai)(dai)护(hu)(hu)坡及水(shui)(shui)平铺盖下均铺设300g/m2无(wu)纺布(bu)反滤。

工(gong)(gong)(gong)程(cheng)区(qu)所在地内(nei)大多数(shu)区(qu)域为(wei)冲(chong)积(ji)层，仅(jin)在河道两(liang)岸分布(bu)有(you)冲(chong)洪积(ji)的粉砂(sha)、砂(sha)壤土和(he)河卵砂(sha)石(shi)，周边缺乏常规格宾石(shi)笼丁坝(ba)所需(xu)的大量(liang)块石(shi)，工(gong)(gong)(gong)程(cheng)比选后采用无纺布(bu)土工(gong)(gong)(gong)袋丁坝(ba)。依(yi)据工(gong)(gong)(gong)程(cheng)地质报告及相关规范，工(gong)(gong)(gong)程(cheng)区(qu)场内(nei)粉砂(sha)、砂(sha)壤土和(he)河卵砂(sha)石(shi)，可(ke)(ke)作为(wei)无纺土工(gong)(gong)(gong)袋丁坝(ba)填筑材料，可(ke)(ke)就(jiu)近取土，方便工(gong)(gong)(gong)程(cheng)施工(gong)(gong)(gong)。

工程(cheng)(cheng)(cheng)(cheng)在河(he)流弯道凹岸400mm水(shui)毁(hui)范围内依次设置6条无(wu)纺(fang)布短丁(ding)坝(ba)(ba)(ba)，坝(ba)(ba)(ba)间间距均为(wei)50m，各丁(ding)坝(ba)(ba)(ba)长(zhang)度(du)尺寸依次为(wei)：8m、10m、15m、20m、25m、15m，丁(ding)坝(ba)(ba)(ba)顺(shun)水(shui)流方向与(yu)坝(ba)(ba)(ba)轴线呈45°夹角(jiao)布置，坝(ba)(ba)(ba)顶高(gao)(gao)程(cheng)(cheng)(cheng)(cheng)较护岸工程(cheng)(cheng)(cheng)(cheng)低1.2m，与(yu)坝(ba)(ba)(ba)址处河(he)道最(zui)大(da)水(shui)位高(gao)(gao)程(cheng)(cheng)(cheng)(cheng)相当，坝(ba)(ba)(ba)底基础高(gao)(gao)程(cheng)(cheng)(cheng)(cheng)参(can)考河(he)床高(gao)(gao)程(cheng)(cheng)(cheng)(cheng)、计算局部冲深及土(tu)工袋模数综合确定。丁(ding)坝(ba)(ba)(ba)裹头超出护岸工程(cheng)(cheng)(cheng)(cheng)水(shui)平铺盖(gai)部分及丁(ding)坝(ba)(ba)(ba)基础下(xia)均铺设300g/m2无(wu)纺(fang)布反滤(lv)，反滤(lv)无(wu)纺(fang)布与(yu)铺盖(gai)下(xia)铺设的无(wu)纺(fang)布相连接，在丁(ding)坝(ba)(ba)(ba)裹头坡(po)脚外侧设置木(mu)桩(zhuang)护脚。