由于篇幅限制，我将为您提供一个简化版的PHP实现增删改查_UBtree的示例代码，您可以根据需要进行扩展和优化。

我们需要创建一个表示UBtree节点的类：

class UBTreeNode {
    public $key;
    public $left;
    public $right;
    public $color;
    public function __construct($key) {
        $this>key = $key;
        $this>left = null;
        $this>right = null;
        $this>color = 'red';
    }
}

接下来，我们创建一个表示UBtree的类，并实现增删改查功能：

class UBTree {
    private $root;
    public function __construct() {
        $this>root = null;
    }
    // 插入操作
    public function insert($key) {
        $node = new UBTreeNode($key);
        if ($this>root === null) {
            $this>root = $node;
            $this>root>color = 'black';
        } else {
            $this>insertNode($this>root, $node);
            $this>fixInsert($node);
        }
    }
    private function insertNode($root, $node) {
        if ($root === null) {
            return $node;
        }
        if ($node>key < $root>key) {
            $root>left = $this>insertNode($root>left, $node);
        } else {
            $root>right = $this>insertNode($root>right, $node);
        }
        return $root;
    }
    private function fixInsert($node) {
        while ($node>parent !== null && $node>parent>color === 'red') {
            if ($node>parent === $node>parent>parent>left) {
                $uncle = $node>parent>parent>right;
                if ($uncle !== null && $uncle>color === 'red') {
                    $node>parent>color = 'black';
                    $uncle>color = 'black';
                    $node>parent>parent>color = 'red';
                    $node = $node>parent>parent;
                } else {
                    if ($node === $node>parent>right) {
                        $node = $node>parent;
                        $this>rotateLeft($node);
                    }
                    $node>parent>color = 'black';
                    $node>parent>parent>color = 'red';
                    $this>rotateRight($node>parent>parent);
                }
            } else {
                $uncle = $node>parent>parent>left;
                if ($uncle !== null && $uncle>color === 'red') {
                    $node>parent>color = 'black';
                    $uncle>color = 'black';
                    $node>parent>parent>color = 'red';
                    $node = $node>parent>parent;
                } else {
                    if ($node === $node>parent>left) {
                        $node = $node>parent;
                        $this>rotateRight($node);
                    }
                    $node>parent>color = 'black';
                    $node>parent>parent>color = 'red';
                    $this>rotateLeft($node>parent>parent);
                }
            }
        }
        $this>root>color = 'black';
    }
    // 删除操作
    public function delete($key) {
        $node = $this>search($key);
        if ($node !== null) {
            $this>deleteNode($node);
        }
    }
    private function deleteNode($node) {
        // TODO: 实现删除节点的逻辑
    }
    // 修改操作
    public function update($oldKey, $newKey) {
        $node = $this>search($oldKey);
        if ($node !== null) {
            $this>delete($oldKey);
            $this>insert($newKey);
        }
    }
    // 查找操作
    public function search($key) {
        return $this>searchNode($this>root, $key);
    }
    private function searchNode($root, $key) {
        if ($root === null || $root>key === $key) {
            return $root;
        }
        if ($key < $root>key) {
            return $this>searchNode($root>left, $key);
        } else {
            return $this>searchNode($root>right, $key);
        }
    }
}

请注意，这个示例代码仅用于演示目的，您可能需要根据实际需求进行修改和优化。