我如何使用simplexml_load_string（）将以下xml转换为可用的php对象？
<soapenv:envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/">
<env:header xmlns:env="http://schemas.xmlsoap.org/soap/envelope/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
<soapenv:body>
<v10:ratereply xmlns:v10="http://fedex.com/ws/rate/v10">
<v10:highestseverity xmlns:env="http://schemas.xmlsoap.org/soap/envelope/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">SUCCESS</v10:highestseverity>
<v10:notifications xmlns:env="http://schemas.xmlsoap.org/soap/envelope/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
<v10:severity>SUCCESS</v10:severity>
<v10:source>crs</v10:source>
<v10:code>0</v10:code>
<v10:message>Request was successfully processed. </v10:message>
<v10:localizedmessage>Request was successfully processed. </v10:localizedmessage>
</v10:notifications>
<v10:transactiondetail>
<v10:customertransactionid></v10:customertransactionid>
</v10:transactiondetail>
<v10:version>
<v10:serviceid>crs</v10:serviceid>
<v10:major>10</v10:major>
<v10:intermediate>0</v10:intermediate>
<v10:minor>0</v10:minor>
</v10:version>
<v10:ratereplydetails xmlns:env="http://schemas.xmlsoap.org/soap/envelope/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
<v10:servicetype>FIRST_OVERNIGHT</v10:servicetype>
<v10:packagingtype>YOUR_PACKAGING</v10:packagingtype>
<v10:deliverystation>TCMA </v10:deliverystation>
<v10:deliverydayofweek>THU</v10:deliverydayofweek>
<v10:deliverytimestamp>2011-06-16T08:30:00</v10:deliverytimestamp>
<v10:commitdetails>
<v10:servicetype>FIRST_OVERNIGHT</v10:servicetype>
<v10:committimestamp>2011-06-16T08:30:00</v10:committimestamp>
<v10:dayofweek>THU</v10:dayofweek>
<v10:destinationservicearea>A2</v10:destinationservicearea>
<v10:brokertodestinationdays>0</v10:brokertodestinationdays>
<v10:documentcontent>NON_DOCUMENTS</v10:documentcontent>
</v10:commitdetails>
<v10:destinationairportid>SEA</v10:destinationairportid>
<v10:ineligibleformoneybackguarantee>false</v10:ineligibleformoneybackguarantee>
<v10:originservicearea>A2</v10:originservicearea>
<v10:destinationservicearea>A2</v10:destinationservicearea>
<v10:signatureoption>SERVICE_DEFAULT</v10:signatureoption>
<v10:actualratetype>PAYOR_ACCOUNT_PACKAGE</v10:actualratetype>
<v10:ratedshipmentdetails>
<v10:shipmentratedetail>
<v10:ratetype>PAYOR_ACCOUNT_PACKAGE</v10:ratetype>
<v10:ratescale>6</v10:ratescale>
<v10:ratezone>2</v10:ratezone>
<v10:pricingcode>PACKAGE</v10:pricingcode>
<v10:ratedweightmethod>ACTUAL</v10:ratedweightmethod>
<v10:dimdivisor>194</v10:dimdivisor>
<v10:fuelsurchargepercent>16.5</v10:fuelsurchargepercent>
<v10:totalbillingweight>
<v10:units>LB</v10:units>
<v10:value>1.0</v10:value>
</v10:totalbillingweight>
<v10:totalbasecharge>
<v10:currency>USD</v10:currency>
<v10:amount>46.3</v10:amount>
</v10:totalbasecharge>
<v10:totalfreightdiscounts>
<v10:currency>USD</v10:currency>
<v10:amount>0.0</v10:amount>
</v10:totalfreightdiscounts>
<v10:totalnetfreight>
<v10:currency>USD</v10:currency>
<v10:amount>46.3</v10:amount>
</v10:totalnetfreight>
<v10:totalsurcharges>
<v10:currency>USD</v10:currency>
<v10:amount>7.64</v10:amount>
</v10:totalsurcharges>
<v10:totalnetfedexcharge>
<v10:currency>USD</v10:currency>
<v10:amount>53.94</v10:amount>
</v10:totalnetfedexcharge>
<v10:totaltaxes>
<v10:currency>USD</v10:currency>
<v10:amount>0.0</v10:amount>
</v10:totaltaxes>
<v10:totalnetcharge>
<v10:currency>USD</v10:currency>
<v10:amount>53.94</v10:amount>
</v10:totalnetcharge>
<v10:totalrebates>
<v10:currency>USD</v10:currency>
<v10:amount>0.0</v10:amount>
</v10:totalrebates>
<v10:surcharges>
<v10:surchargetype>FUEL</v10:surchargetype>
<v10:description>Fuel</v10:description>
<v10:amount>
<v10:currency>USD</v10:currency>
<v10:amount>7.64</v10:amount>
</v10:amount>
</v10:surcharges>
</v10:shipmentratedetail>
<v10:ratedshipmentdetails>
</v10:ratereplydetails>
</v10:ratereply>
</soapenv:body>
</env:header>